vn.kayak.com cũng có sẵn bằng tiếng Anh. Visit site in English.

Tìm những chuyến bay giá rẻ từ Seattle đến Đà Nẵng

SEA - DAD

Tìm những chuyến bay giá rẻ từ Seattle đến Đà Nẵng

Tìm kiếm hàng trăm trang web du lịch cùng lúc để tìm những ưu đãi cho những chuyến bay đến Đà Nẵng

Khứ hồi
Phổ thông
Seattle (SEA)
Đà Nẵng
Th 4 14/4
Th 4 21/4
Any month
So sánh với KAYAK |

Bạn nên biết

Mùa thấp điểm

Tháng TámThời điểm tốt nhất để tránh đám đông với mức giá trung bình giảm 24%.

Mùa cao điểm

Tháng Mười haiThời gian bay phổ biến nhất với mức giá tăng trung bình 37%.

Giá trung bình cho khứ hồi

19.852.108 ₫(giá trung bình cho 2 tuần qua)

Giá tốt cho khứ hồi

17.309.606 ₫trở xuống

Khi nào nên đặt vé máy bay từ Seattle đến Đà Nẵng

Giá khứ hồi theo ước đoán
Giá trung bình mỗi tháng
Giá vé khi đến gần ngày đi

Những mẹo hay nhất để tìm vé giá rẻ

  • Tìm vé máy bay giá rẻ? 25% người dùng của chúng tôi tìm được vé khứ hồi cho đường bay này với giá 17.309.606 ₫ trở xuống.
  • Tính trung bình, giá vé rẻ nhất cho chuyến bay từ Seattle tới Đà Nẵng được tìm thấy 89 ngày trước khi bay.
  • Hãy đặt vé ít nhất 3 tuần trước khi khởi hành để được mức giá thấp hơn mức trung bình.
  • Mùa cao điểm thường là Tháng Mười một, Tháng Mười hai và Tháng Một. Tháng bạn có thể mua vé máy bay rẻ nhất là Tháng Tám.

Câu hỏi thường gặp khi đặt vé máy bay từ Seattle đến Đà Nẵng

Chuyến bay từ Seattle đến Đà Nẵng kéo dài bao lâu?

Vé máy bay từ Seattle đến Đà Nẵng của hãng nào rẻ nhất?

Sân bay nào tôi sẽ dùng khi bay từ Seattle đến Đà Nẵng?

Làm thế nào KAYAK tìm được những mức giá thấp đến thế cho những chuyến bay từ Seattle đến Đà Nẵng?

Làm thế nào công cụ Dự báo giá chuyến bay của KAYAK giúp tôi chọn được thời điểm phù hợp để mua vé máy bay từ Seattle đến Đà Nẵng?

Thế nào là phương án KAYAK Mix cho những chuyến bay từ Seattle đến Đà Nẵng?

Thế nào là tính năng "ngày linh hoạt" của KAYAK và tại sao tôi nên để tâm đến thời điểm cần tìm một chuyến bay từ Seattle đến Đà Nẵng?

Những hãng bay hàng đầu bay Seattle/Tacoma Intl đến Đà Nẵng

Điểm theo đánh giá của khách hàng KAYAK

8,6
Singapore Airlines
Điểm tổng thể dựa trên 3.883 đánh giá
8,8
Lên máy bay
8,5
Thư thái
8,9
Phi hành đoàn
8,6
Thư giãn, giải trí
8,3
Thức ăn
Đánh giá hãng bay

Ưu: "the crew is fine. The seat was OK standard."
Khuyết điểm: "Food was not good on my way back to L.A. Food was no flavor, pork cut up way too big, prefer having small piece of meat soaked up flavor sauce."

Ưu: "Crew were amazing and great entertainment"
Khuyết điểm: "Boarding could be better"

Ưu: "I like the crew members"
Khuyết điểm: "Entertainment selection and food could be better"

Ưu: "Entertainment system was new and easy to use. Seats in premium economy were quite comfortable."
Khuyết điểm: "A vegetarian / pescatarian option on the menu would have been nice but other than that, all good."

Ưu: "Crew very attentive but not intrusive. Food very good."
Khuyết điểm: "I did not find much to watch on entertainment system. Have to get crew to assemble flat bed, a bit of a nuisance. Also to turn it back into a chair."

Ưu: "Crew , amenities and food"
Khuyết điểm: "None"

Ưu: "Amazing crew, great seating area and tasty menu."

Khuyết điểm: "The lunch part at the end was a little late we had just had a snack and a small sandwich so we didn't eat a lot. But food was great!"

Khuyết điểm: "Flat beds on second flight"

Khuyết điểm: "No complain . It’s singapore airlines"

Ưu: "Crew was friendly. Seafood pasta was good."
Khuyết điểm: "I wish all airlines have a foot rest."

Ưu: "Seats with entertainment"

Ưu: "Great crew and cabin!"
Khuyết điểm: "Meals were just ok"

Ưu: "Dim sum between Hong Kong & Singapore."

Khuyết điểm: "My moslem meal selection wasn’t provided onboard"

Ưu: "Everything"
Khuyết điểm: "N/A"

Ưu: "Wow they did not disappoint flight attendants Overdid themselves with amazing service planes are super clean and entertainment systems are state of the art great job Singapore Airlines can’t wait to fly with you again you definitely earned your #1 ranking"

Ưu: "Staff are great and on board service was good. Boarding is always well organised from Changi however it was a full flight and as always half the passengers exceeded their carry on allowance. Rather than addressing this bags were flung everywhere no nowhere within your actual reach during the flight. Very annoying when you are a passenger who does the right thing."
Khuyết điểm: "See above. No in flight entertainment makes you feel like you're flying with the low cost carrier rather than a full service airline."

Ưu: "Very comfortable. best airline I flew on overall and was first time ."
Khuyết điểm: "Charges for extra bag was steep- $150. Location at LAX airport is far. While nice to have many options for meal but did not low-carb so I only ate half my food"

Ưu: "They were polite."
Khuyết điểm: "Not as attentive as ANA or China Airlines. I had to give 4-5 request to get what I want."

Khuyết điểm: "With no food preferences specified, it takes a significantly longer time to get your meal as there are a lot of people who have special dietary requirements on certain routes."

Ưu: "Singapore has always been my preferred airline because they give excellent service, excellent food and the crew are very polite. aircraft new and comfortable, I finally had a flatbed"
Khuyết điểm: "the call button did not work the tray table was almost impossible to pull in and out (BC)"

Khuyết điểm: "The desserts. The bun."

Ưu: "I was inpressed"

Ưu: "Singapore was fine and helpful with a crazy problem JustFly created then didn’t fix."
Khuyết điểm: "JustFly billed the wrong price, then to fix that,created a new ticket with my name misspelled and failed to cancel the original ticket. We later upgrade seats via Singapore then discovered the duplicate booking and misspelling. To fix that JustFly cancelled the booking with the seat upgrade. Singapore restored our upgrade at the airport but only on one direction so we had to go through it all again."

Ưu: "I like everything about Singapore airline service."
Khuyết điểm: "Nil"

Ưu: "Business seats were excellent"
Khuyết điểm: "All was good!"

Khuyết điểm: "Crew woke me up from deep sleep to raise seatback for meal service. Sleep versus food?? Should prioritise sleep every time on night flights."

Ưu: "The cabin crew was great."
Khuyết điểm: "1. Flight seats are too congested on flight.. 2. Not too many indian movie choices 3. Some reason, while booking the flight, the KAYAK site had not asked for food choice. And the airline does not carry any extra vegetarian food. This had caused some inconvenience."

Ưu: "The crew on this flight we amazing had a great flight Thank You"

Ưu: "The seats seem to have more leg room, food was actually good, and the staff was delightful."
Khuyết điểm: "It was a 17 hour flight, but they made it bearable."

Ưu: "Seats, crew"
Khuyết điểm: "Nothing else other than above"

Khuyết điểm: "Na"

Ưu: "To be honest I had a pretty bad flight because my allergies exploded during the entire flight - constant sneezing, runny nose, you name it. However, the attentiveness of the crew really made up for it. The cabin was decorated with tiny wreathes (so cute!), and the pillow/blanket was very comfortable/warm for an Economy seat. Although I did not use it as much, the entertainment seemed top-notch. And the crew-- they noticed that I was not feeling well, and offered me peppermint tea and snacks that did sooth things a bit (you can request for snack/beverage refills anytime!). I loved that they gave out black socks to the passengers too (I prefer taking my shoes off during the flight, so the socks added warmth & prevented my own socks from getting dirty). All in all, it was one of the best-serviced long flights I had, not to mention probably the most affordable price I paid for my annual trip to Korea (from LA)."

Ưu: "Food was good"

Ưu: "Seats!!"
Khuyết điểm: "Not enough vegetarian options. Food not that great for business class. Not enough English new release movies. Many were old. Could be improved."

Ưu: "The service and fast flight"
Khuyết điểm: "N/A"

Khuyết điểm: "It is really good experience. All the flight attendants are good"

Ưu: "Such incredible staff. Always Willing to go above and beyond! I flew 17 hours with them and they made the flight a breeze. Great airline, will be flying with Singapore again"
Khuyết điểm: "Really nothing. I loved flying with them."

Ưu: "Very helpful and polite staff"
Khuyết điểm: "Old B777-200 with small personal screen. And they don't have pillows on board."

Ưu: "Staff friendly and efficient"

Ưu: "Friendliness of crew"

Ưu: "everything, excellent job"

Ưu: "First class airline. Great flight, great service, and even the food is better than "not bad". Seriously, Singapore Air offers flights between the U.S. and Asia at very competitive rates, but never seems to skimp on customer care. A well-done experience from start to finish..."

Ưu: "Excellent crew, efficient processes and overall relaxing"
Khuyết điểm: "Old business class hard product. Seats can't be adjusted much and the bed is too short due to small head- and footwell."

Ưu: "My luggage was lost, due to an error of another airline. but singapore air took care of it and made sure i got the luggage in Germany - even though it involved bringing it to me to remote location 2.5 hour drive from frankfurt. free of charge. Thanks Singapore airlines!"

Ưu: "Crew was very attentive and professional"
Khuyết điểm: "Return flight the movies were the same as three weeks earlier."

Ưu: "Great food and plenty of movies. Friendly crew"

Ưu: "Had a row to myself to stretch out. Not crowded, no wait for bathrooms. I like the warm washcloths after we settled in and before meals. Plenty of blankets and pillows."
Khuyết điểm: "Food was ok, not super high quality."

Khuyết điểm: "Only the space was lacking...not a lot of room for such a long flight and having to sleep. But it was okay!"

Ưu: "The crew was nice, the food was good. We did miss our first flight, so we were automatically rebooked on a new flight."
Khuyết điểm: "We missed our first flight because of our connection."

Khuyết điểm: "Terrible service. It’s a nightmare to fly with. And I have a baby with me that even worse to fly with Eva."

Ưu: "Everything great"

Ưu: "Eva does a great job, nice personnel, good food...probably better than most."
Khuyết điểm: "More leg room. (My usual complaint,) Premium Economy Very Nice, but at a premium price. I flew once...nice to be offered a glass of Champagne once seated!"

Ưu: "Flight crew"
Khuyết điểm: "No leg room"

Khuyết điểm: "Was not able to board"

Ưu: "Crew was great and were timely in boarding and deplaning processes. They were willing to help when asked."
Khuyết điểm: "As a 6’ tall, broad shoulder individual the seats were narrow and there was not much leg room. Fortunately there was an empty seat directly next to me which afforded me some space."

Ưu: "Economy seats were EXTREMELY uncomfortable, a mannequin would complain and to add insult to injury , the obvious placements of overly extravagant “first class” seats vs regular economy seats , were very off putting. People are sitting on cardboard for hours on end , add some comfort to your seats!"
Khuyết điểm: "More humanly comfortable seats , I understand you get what you pay for, but having to be deliberately uncomfortable for 13 hours straight is extremely unfair."

Ưu: "The seat was comfortable. The crew was very nice."
Khuyết điểm: "Keep doing the same. Cost is not always the most important."

Khuyết điểm: "My first meal was kind of burnt, and I wish they would offer a salt and pepper packets. Also, more frequent Rounds to pick up trash would be helpful"

Ưu: "Comfortable and excellent hospitality."
Khuyết điểm: "None."

Khuyết điểm: "Alaska missing my​ suitcases I​ could not​ get​ them​ on​ time​ made​ me​ annoying"

Ưu: "Flight attendants were all nice and friendly."

Ưu: "The seats were OK, solid C. The staff were good B+, and the food (warm veggie was poor D+. The second flight I had raw veggies which was much better, B-."
Khuyết điểm: "The flight from Taipei to BKK too off 40 minutes late. When we arrived in Thailand it took 20 minutes to get the jetway working. Sad! Timely flights and support services are expected."

Khuyết điểm: "Seating way too tight"

Ưu: "EVA isn't a discount airline. Being the National Airline of Taiwan and a member of the STAR alliance, you will pay a premium price. I was originally being put in a row right behind the bulkhead with no individual monitor and a seat that was extremely cramped because of the tray table. I knew that I would be able to hang for a 13 hour flight and fortunately, the flight attendant was able to move my wife and I."
Khuyết điểm: "Only one current movie available. Food was bland and not very appetizing."

Ưu: "EVA crew was wonderful and hardworking"
Khuyết điểm: "Did not like our seats and weight limits for carry on"

Ưu: "They very helpfull"
Khuyết điểm: "The chair was too small"

Ưu: "I’ve always had a great flight with them. Crew always very nice and very helpful."
Khuyết điểm: "I have nothing bad to say. Maybe it there was a little more entertainment more movies and tv shows."

Ưu: "Very comfortable flight, crew were very professional, food was delicious!"
Khuyết điểm: "Wish I had known the headphone jack needed and adapter from mono to stereo to use own headphones, but the headphones provided were adequate."

Khuyết điểm: "Baggage rules on itinerary didn’t match reality. Baggage 7kg was enforced, check in bags almost empty as documents & computers weigh a lot, and cant be trusted to “check-in”. If I had know we could check in four bags free it would have made a big difference. The itinerary says one each, plus one for Premier status, which adds up to three in our case. Not a happy camper. Will avoid EVA when there are other good choices. My wife had advised against EVA to begin with, check-in confirmed her advice. Crew didn’t come by much with water or juice, but they were courteous. Seat belt sign was put on when bumpy, but not turned off for the next hour or two of smooth sailing. “I told you so” was here reaction . . . ."

Ưu: "Cute and friendly flight attendants. Food was very tasty. Seat were amazingly comfy - no probs with sore bottom. Cabin area clean. Check-in was very easy."
Khuyết điểm: "Think seats maybe 1-2" (2.5-5cm) closer than Asiana - knees hitting seat in front and if person leaned seat back, it would hurt."

Ưu: "I really enjoyed the flight seated in the exit row 45. I was amazed at the on board service. The attendants moved quickly also in a run without the usual frowns that I’ve seen on other airlines."
Khuyết điểm: "The exit row seat 45C was too narrow. The cup of coffee I had near the end of flight tasted like halve coffee halve tea. Also the checkin line was too slow. There appeared to be more clocks standing around instead of attending the customers trying to check in."

Ưu: "Very comfortable. Great movies."
Khuyết điểm: "Not so good on the television shows"

Ưu: "I cannot say how much i enjoyed eva air. The stewardesses were wonderful the people in taipei i dealt with were fantastic."
Khuyết điểm: "The woman i had to deal with in seattle at the ticketing desk was an absolute nightmare. Im heartbroken i dont remember her name because i would happily name her. Everyone else was perfect. The fella helping me even said "i am so sorry, she is awful and makes me very nervous. I will probably fly asiana from now on just so i do not have to deal with her."

Ưu: "Never flew with EVA but timely take off and landing. Smooth flight. Kind crew members. I think everything is great because I did not expect a lot from this airlines."
Khuyết điểm: "I don't know much about Chinese food. Announcement was a bit hard to understand their accent."

Ưu: "Friendliness, comfy seats"
Khuyết điểm: "food,"

Ưu: "The crew was very friendly and fast help with passengers needs."
Khuyết điểm: "On long flights over 6 hours , I find that seats become very uncomfortable . I do stand up and stretch if it is available to do so. After 10 hours of flight travel my legs , back, and neck are very stiff and sore."

Ưu: "It's like a well oiled engine, they are very reliable every time I fly with them. The service is good and courteous. The in-flight entertainment is wide ranging. The food is ok. Washroom is clean and fresh."
Khuyết điểm: "More leg room for economy class. :-)"

Ưu: "The cabin crew were nice."

Ưu: "Great food, clean bathrooms, courteous and efficient service. It was my first time flying with EVA Air and I would definitely choose them again."

Ưu: "Reasonable legroom in Economy. Friendly staff. Clean bathrooms."
Khuyết điểm: "Beer selection is terrible (eww - Heineken) Movie selection is very limited"

Khuyết điểm: "I did not like the transfer from Eva to air Macau. Horrible. Long walk. No one there. No lounge to wait 5 hours!! I hate what happened"

Khuyết điểm: "Person in front of me reclined their seat to far and made it very uncomfortable"

Ưu: "Nice staff good movie selection good flight"

Ưu: "The price the food okay. The leg room seemed more in economy than other airlines."
Khuyết điểm: "Not just your airline but a cultural differences how westerners take how they are talked too"

Ưu: "Without fail, every EVA flight crew is professional and kind the perfect combination for long flights."

Khuyết điểm: "Wasn't able to confirm seats ahead of time. The option to order a vegetarian meal would have been good. Wasn't able to do either of these things through kayak or eva websites and there were no option once on board."

Khuyết điểm: "The 6 hours layover"

Ưu: "The flight crew was amazing. They were very kind and helpful"
Khuyết điểm: "I'd work on the in flight food"

Ưu: "Everything is perfect"
Khuyết điểm: "Nothing"

Ưu: "I had a ile seat,and wasn't crowded"
Khuyết điểm: "Nothing."

Ưu: "Crew always pleasant service good. Seats comfortable"
Khuyết điểm: "All good"

Khuyết điểm: "Flight crew was unfriendly with myself and other passengers."

Ưu: "The service was fantastic, the food was great, the plane was in great shape, overall a great experience - I'd certainly fly again!"

Ưu: "relatively more spacious than other airlines"
Khuyết điểm: "seat itself not comfortable enough, hard seat; food can perhaps be improved"

Ưu: "fantastic flight experience. the aircraft was clean neat and comfortable. i loved how they kept the restrooms so clean even through a 13.5 hour flight. I slept through dinner but the western style breakfast was good. The crew was attentive and polite."

Ưu: "Awesome flight...on time and good food.. customer service was excellent"

Ưu: "Staff"
Khuyết điểm: "Bad bad bad I book 3 months ahead, they should put us in the front row seat instead so far to the back seat."

Đọc thêm về Singapore Airlines
Thông tin về COVID-19

Những biện pháp an toàn cho những hãng bay có chuyến bay từ Seattle đến Đà Nẵng

Những hãng bay có chuyến bay từ Seattle đến Đà Nẵng đã thực hiện thêm những biện pháp an toàn và điều chỉnh các chính sách để thích ứng tốt hơn với du khách. Các chính sách khác nhau tuỳ vào hãng bay.

Tăng cường vệ sinh

Lau chùi hằng ngày, lắp đặt các màng lọc HEPA cho cabin trên những chuyến bay từ Seattle đến Đà Nẵng

Khẩu trang bắt buộc

Cần đeo khẩu trang khi lên máy bay, khẩu trang được cung cấp cho các chuyến bay từ Seattle đến Đà Nẵng

Xếp ghế ngồi giữ cự ly xã giao

Ghế ngồi ở giữa không đặt được cho những chuyến bay từ Seattle đến Đà Nẵng

Xét nghiệm trước khi bay

Xét nghiệm kháng thể, xét nghiệm triệu chứng cho các chuyến bay từ Seattle đến Đà Nẵng

Đặt chuyến bay rẻ từ Seattle đến Đà Nẵng

Những ưu đãi gần đây cho chuyến bay khứ hồi

6/10
Th 4
3 điểm dừng
Singapore Airlines
34h 55m
SEA - DAD
27/10
Th 4
1 điểm dừng
Singapore Airlines
34h 50m
DAD - SEA
5/10
Th 3
1 điểm dừng
EVA Air
20h 05m
SEA - DAD
27/10
Th 4
1 điểm dừng
EVA Air
15h 30m
DAD - SEA
18/7
CN
1 điểm dừng
Nhiều hãng bay
19h 55m
SEA - DAD
28/7
Th 4
2 điểm dừng
Nhiều hãng bay
22h 40m
DAD - SEA
25/9
Th 7
1 điểm dừng
Singapore Airlines
34h 45m
SEA - DAD
29/9
Th 4
1 điểm dừng
Singapore Airlines
30h 10m
DAD - SEA
6/10
Th 4
3 điểm dừng
Singapore Airlines
39h 35m
SEA - DAD
27/10
Th 4
3 điểm dừng
Singapore Airlines
58h 53m
DAD - SEA
18/7
CN
1 điểm dừng
EVA Air
19h 25m
SEA - DAD
28/7
Th 4
1 điểm dừng
EVA Air
19h 55m
DAD - SEA
19/7
Th 2
1 điểm dừng
Singapore Airlines
39h 25m
SEA - DAD
28/7
Th 4
1 điểm dừng
Singapore Airlines
34h 50m
DAD - SEA
24/9
Th 6
1 điểm dừng
Nhiều hãng bay
20h 05m
SEA - DAD
29/9
Th 4
2 điểm dừng
Nhiều hãng bay
20h 04m
DAD - SEA
24/9
Th 6
1 điểm dừng
EVA Air
20h 35m
SEA - DAD
29/9
Th 4
1 điểm dừng
EVA Air
19h 20m
DAD - SEA
25/9
Th 7
1 điểm dừng
Singapore Airlines
34h 45m
SEA - DAD
29/9
Th 4
3 điểm dừng
Singapore Airlines
54h 13m
DAD - SEA
25/9
Th 7
2 điểm dừng
Singapore Airlines
26h 45m
SEA - DAD
29/9
Th 4
1 điểm dừng
Singapore Airlines
34h 50m
DAD - SEA
5/10
Th 3
2 điểm dừng
Nhiều hãng bay
22h 40m
SEA - DAD
27/10
Th 4
2 điểm dừng
Nhiều hãng bay
21h 10m
DAD - SEA
19/7
Th 2
1 điểm dừng
Singapore Airlines
39h 25m
SEA - DAD
28/7
Th 4
2 điểm dừng
Singapore Airlines
40h 15m
DAD - SEA
19/7
Th 2
3 điểm dừng
Nhiều hãng bay
47h 50m
SEA - DAD
28/7
Th 4
3 điểm dừng
Nhiều hãng bay
41h 26m
DAD - SEA
19/7
Th 2
1 điểm dừng
Singapore Airlines
39h 25m
SEA - DAD
28/7
Th 4
3 điểm dừng
Singapore Airlines
53h 41m
DAD - SEA
24/9
Th 6
2 điểm dừng
Nhiều hãng bay
23h 50m
SEA - DAD
29/9
Th 4
2 điểm dừng
Nhiều hãng bay
18h 20m
DAD - SEA
25/9
Th 7
2 điểm dừng
Singapore Airlines
26h 45m
SEA - DAD
29/9
Th 4
3 điểm dừng
Singapore Airlines
54h 13m
DAD - SEA
25/9
Th 7
3 điểm dừng
Singapore Airlines
39h 35m
SEA - DAD
29/9
Th 4
3 điểm dừng
Singapore Airlines
54h 13m
DAD - SEA
6/10
Th 4
2 điểm dừng
Nhiều hãng bay
27h 35m
SEA - DAD
26/10
Th 3
1 điểm dừng
Nhiều hãng bay
24h 25m
DAD - SEA
18/7
CN
2 điểm dừng
Nhiều hãng bay
26h 40m
SEA - DAD
28/7
Th 4
2 điểm dừng
Nhiều hãng bay
36h 25m
DAD - SEA
Hiển thị thêm kết quả
-
1
  • Khứ hồi
  • Một chiều
  • Nhiều thành phố
  • Phổ thông
  • Phổ thông đặc biệt
  • Thương gia
  • Hạng nhất
  • Nhiều hạng
Phổ thông
  • Phổ thông
  • Phổ thông đặc biệt
  • Thương gia
  • Hạng nhất
Phổ thông
  • Phổ thông
  • Phổ thông đặc biệt
  • Thương gia
  • Hạng nhất
Phổ thông
  • Phổ thông
  • Phổ thông đặc biệt
  • Thương gia
  • Hạng nhất
Phổ thông
  • Phổ thông
  • Phổ thông đặc biệt
  • Thương gia
  • Hạng nhất
Phổ thông
  • Phổ thông
  • Phổ thông đặc biệt
  • Thương gia
  • Hạng nhất
Phổ thông
  • Phổ thông
  • Phổ thông đặc biệt
  • Thương gia
  • Hạng nhất