1) How full is this plane?
「この飛行機どのくらい混んでますか？」
how full を使って混み具合を聞くことができます。
2) Is this plane pretty empty still?
「この飛行機はまだ結構空いてますか？」
逆に「混んでますか？」と聞くなら
3) Is this plane quite full?
「この飛行機は結構混んでますか？」
ご参考になれば幸いです！
There are many ways to ask airline staff if a flight is full, or if there are more seats available. The most simple way would be "Is this flight full?" Another way to say it is "Is this flight fully booked?" with "fully booked" meaning that all of the seats are reserved and there are no more available. Depending on how friendly the staff member is, they might just give you a simple yes or no answer for both of these question forms. So if you are hoping to find out about how many seats are still available, you might want to ask "Are there any seats left on this flight?" In this form, they might be encouraged to tell you that there are a few seats left, or maybe many seats left if it is not a crowded flight.
航空会社のスタッフに飛行機に空席があるかどうか確認するなら、これはいろいろな聞き方ができます。
最もシンプルな言い方は "Is this flight full?"（この飛行機は満席ですか）です。
他に、"Is this flight fully booked?"（この飛行機は満席ですか）と言うこともできます。"fully booked" は、席が全て予約で埋まっていて一つも残っていないことを表します。スタッフがどのくらい親切な人かにもよりますが、これら二つの質問には単に「はい」か「いいえ」でしか答えてくれないかもしれません。
席が何席残っているか確認したいなら、
"Are there any seats left on this flight?"（この飛行機にはまだ空席はありますか）
と聞いた方がいいかもしれません。
これなら、「数席残っている」や、あるいは混んでいない飛行機なら「たくさん残っている」などと教えてくれるかもしれません。
Is the plane crowded? - The word "crowded" means that there are a lot of people or things in one area. For example "Time Square in New York is always crowded".
How full is the flight? - The word "full" means reaching maximum amount. The person could reply with "It's not that full" or "it's pretty full".
Are there many seats left on the plane? - The word "left" in this sentence is not a direction but rather how many seats on the plane that are still available.
Is the plane crowded?（飛行機は満員ですか）
→"crowded" は一つの場所にたくさんの人または物が集まっている状態をいいます。
例えば：
"Time Square in New York is always crowded"（ニューヨークのタイムズスクエアはいつも人でいっぱいです）
How full is the flight?（飛行機はどのくらい混んでいますか）
→"full" は「限度量に達した」という意味です。この質問には "It's not that full"（そんなに混んでいません）や "It's pretty full"（かなり混んでいます）などと答えることができます。
Are there many seats left on the plane?（飛行機に空席はたくさん残っていますか）
→この文の "left" は「左」という意味ではなく、飛行機に空席がどのくらい「残っている」かを表します。
When talking about how many people will be attending or going on something, to find out how many people will be doing this we can ask 'how full' or 'how busy' something will be
To ask in a nice polite way we can add please
Is the plane pretty crowded or are there still available seats?
Is there much room on the plane right now?
When we say "pretty crowded" it is implied that the flight is already somewhat full. That is to say not completely full but almost and with many people. "Available seats" refers to the seats that are accessible and not occupied by anyone else.
When we say "Much room" we are portraying that we already know that the plane is filling up and that many seats are already taken.
Is it a full flight? is the direct way to enquire if the plane will be crowded or not, however, it will only encourage a yes or no answer and wont give you any idea as to how full or empty it is.
Asking if there are many empty seats or if all seats are all taken are more indirect ways to ask about how full the plane and may prompt the assistant to tell you how full or empty the flight is.
Is it a full flight?（満席ですか？）は、飛行機が混んでいるかを確認するダイレクトな方法ですが、はいかいいえで答えられる質問なので、どれくらい混んでいるかを聞くことはできないでしょう。
たくさん空席があるか、満席かを聞くのは、その飛行機にどれくらいの余裕があるのかを聞くことができる方法です。
"Are there still seats available on this plane?": We use 'are' because it 'seats' is a plural. This question clearly shows that you are interested is reserving one of these seats.
"Can I still book a seat on this flight?": to book in this context is a verb which means 'to reserve a place'. Therefore, the question means that you want to reserve a place of the plane.
"Is the flight fully booked?": This means 'are all of the seats on the plane already reserved".
"Are there still seats available on this plane?"
（この飛行機にまだ空席はありますか？）
'seats' が複数形なので、 'are' を使っています。この質問は、空席を抑えるのに興味を示していることを表します。
"Can I still book a seat on this flight?"
（このフライトの席はまだ予約できますか？）
:この場合の動詞to bookは、予約するという意味です。ですので、この文は席を予約したいという意味になります。
"Is the flight fully booked?"
（フライトは満席ですか？）
これは、全ての席が予約させているかを聞く文です。
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