by the time+過(guò)去時(shí)間，主句過(guò)去完成。by the time+將來(lái)時(shí)間，主句將來(lái)完成時(shí)。

by the time有兩個(gè)意思

1)到...為止

如果從句中的謂語(yǔ)動(dòng)詞是一般過(guò)去時(shí)，那么主句中的謂語(yǔ)動(dòng)詞通常用過(guò)去完成時(shí)，表示“截止到從句動(dòng)作發(fā)生時(shí)，主句動(dòng)作已經(jīng)完成，即過(guò)去的過(guò)去”

He had left by the time we reached home.

當(dāng)我們到家的時(shí)候他已經(jīng)走了。

2.如果從句中的謂語(yǔ)動(dòng)詞為一般現(xiàn)在時(shí)/或現(xiàn)在完成時(shí)（表示將來(lái)），那么主句中的謂語(yǔ)動(dòng)詞常為將來(lái)完成時(shí)，表示“截止到將來(lái)某一時(shí)間為止，主句動(dòng)作將已經(jīng)完成”

By the time you get back，I shall have finished the work。

到你回來(lái)時(shí)，我將已經(jīng)把活做完了。

2)當(dāng)……的時(shí)候

如果只是說(shuō)過(guò)去某個(gè)時(shí)候的狀況，用過(guò)去時(shí)，而不用完成時(shí)。

By the time we arrived the meeting was over.

我們到達(dá)時(shí)，會(huì)議已結(jié)束了。

by the time雙語(yǔ)例句

By the time you get there the meeting will be over.

等你到了那里的時(shí)候，會(huì)議就該結(jié)束了。

By the time I arrived on the scene, it was all over.

我來(lái)到現(xiàn)場(chǎng)時(shí)，一切都已結(jié)束。

By the time this gets into print, they'll already have left the country.

這篇東西發(fā)表的時(shí)候，他們將已經(jīng)離開(kāi)這個(gè)國(guó)家了。

She was tired and out of sorts by the time she arrived home.

她回到家里，又累又煩。

By the time we arrived, someone had grabbed all the good seats.

我們到達(dá)時(shí)，所有的好位子都給人占了。