英語語法詳解：時間狀語從句

■引導(dǎo)時間狀語從句的從屬連詞

引導(dǎo)時間狀語從句的從屬連詞很多，如較基本的有before, after, when, while, as, since, till, until, as soon as 等：

Things were different when I was a child. 我小時候情況與現(xiàn)在不同。

We must strike while the iron is hot. 我們要趁熱打鐵。

It’s a long time since I met you last. 從上次見到你，已有很長時間了。

He waited until she was about to leave. 他等著一直到她準(zhǔn)備離開。

除以上基本的引導(dǎo)時間狀語從句的從屬連詞外，還有些本來不是從屬連詞卻可用作從屬連詞的詞：

(1) 表示“一…就”的從屬連詞：the moment, the minute, the second, the instant, immediately, directly, instantly, once, no sooner…than, hardly…when等。如：

Immediately he came I told him the news. 他一來我就把消息告訴了他。

The moment I saw him I knew there was no hope. 我一看到他就知道沒希望了。

We had no sooner set out than it began to rain. 我們剛出發(fā)就下雨了。

Once he arrives, we can start. 他一來我們就可以開始。

(2) 涉及time的幾個從屬連詞：every time(每次)，each time(每次)，(the) next time(下次)，any time(隨時)，the last time(上次)，the first time(第一次)。如：

Every time I see her I’ll think of it. 每次我看到她，我就想起這事。

He felt nervous each time she spoke to him. 每次她和他講話，他都感到緊張。

He didn’t tell me the last time I saw him. 我上次見到他時他沒告訴我。

■與時間狀語從句有關(guān)的時態(tài)問題

關(guān)于這個問題有兩點(diǎn)值得注意：

(1) 當(dāng)主句為將來時態(tài)或具有將來意義時，時間狀語從句通常要用一般現(xiàn)在時表示將來意義，而不能直接使用將來時態(tài)：

Turn off the lights before you leave. 走前關(guān)燈。

I will tell him as soon as he arrives. 他一來我就告訴他。

(2) 與since 從句搭配的主句的時態(tài)通常是現(xiàn)在完成時態(tài)：

He has lived here since 1999. 自1999年以來，他就一直住在這兒。

Where have you been since I last saw you? 自我上次見到你之后你到哪里去了?

【注】在特定的語言環(huán)境中有時也可能用過去完成時或一般現(xiàn)在時：

It seems like years since we last met. 我們似乎幾年未見面了。

Yesterday he told me that he hadn’t eaten anything since Tuesday. 他昨天告訴我自星期二以來他一直未吃任何東西。