Question

I hate _____ when people talk with their mouths full

1. A.
   it
2. B.
   that
3. C.
   these
4. D.
   them

Answer 1

A
考查形式賓語。it是形式賓語，真正的賓語是when people talk with their mouths full，因為hate在此處是及物動詞，后面必須加賓語，但是when people talk with their mouths full是一個完整的句子，不能做賓語，就必須用it充當形式賓語。
這個時候when people talk with their mouths full雖然是一個疑問句，但是卻是陳述句的形式，when翻譯成“當……的時候”。when做“當……的時候”講的時候，不一定就是引導時間狀語從句，它可以用于從句中。比如what：I don't believe what you said.
這里的what同樣是疑問詞，也作“什么”講，但是它僅僅是從句的一個成分而已（賓語）。