1. by表示在某特定的時(shí)間之前或不遲于某特定的時(shí)間,意為”最遲在;不遲于”或”在……之前”等。如:

①I will finish my task by nine.我將在九點(diǎn)鐘前完成任務(wù)。

②The plane takes off at 10:00, so you must try to be at the airport by 9:30.飛機(jī)在十點(diǎn)鐘起飛,所以你必須在九點(diǎn)半趕到機(jī)場(chǎng)。

2. until用在肯定句,謂語(yǔ)動(dòng)詞通常是延續(xù)性動(dòng)詞,如stand, stay, talk, wait等,表示主句動(dòng)作終止的時(shí)間。如:

③I waited until he came back.我一直等到他回來。

④The war lasted until 1945.戰(zhàn)爭(zhēng)持續(xù)到1945年。

如果用在否定句,謂語(yǔ)動(dòng)詞通常是瞬間性動(dòng)詞,如open, start, leave, arrive, finish, stop等,強(qiáng)調(diào)主句動(dòng)作開始的時(shí)間。如:

⑤I didn’t leave the boy until his mother turned up.直到這孩子的母親來,我才離開。

⑥The noise of the street didn’t stop until it was midnight.街上的噪音直到半夜才停止。

（來源：滬江英語(yǔ)）