He want it to be his turn.

They love it when the post arrives.

love為及物動(dòng)詞，需要有賓語(yǔ)，但love又不可以接賓語(yǔ)從句。假如想要表示他們喜歡郵件到達(dá)的時(shí)候這個(gè)意義時(shí)，不可以用when從句作love的賓語(yǔ)。于是用虛指it占據(jù)賓語(yǔ)的地方，再用when從句作時(shí)間狀語(yǔ)從句。動(dòng)詞like, hate, take, appreciate都有類似使用方法。比如：

I’ll appreciate it if you can do me a favor.

我喜歡這里，英文是I like it here. 而不是I like here. 副詞here不可以做like的賓語(yǔ)。

He wants it to be his turn. 這是復(fù)合賓語(yǔ)結(jié)構(gòu), 不定式為賓補(bǔ)。

It is not his turn, but he wants it to be his turn.