宾语从句的时态用法详解
语法是语言的组织规律，任何人在使用语言时，不管他是否学过语法，都须合乎语法。
1、主句是一般现在时，从句根据实际情况使用任何时态。
例句：She says (that) she works from Monday to Friday.
她说她从周一至周五上班。(从句是一般现在时）
She says (that) she will leave a message on his desk.
她说她要在他桌子上留个便条。（从句是一般将来时）
2、主句是过去时态，从句须用过去时态的某种形式。
例句：He said there were no classes yesterday afternoon.
他说昨天下午没有课。（从句是一般过去时）
He said (that) he was going to take care of the baby.
他说他会去照看这个婴儿。（从句是过去将来时）
3、当宾语从句表示的是一个客观真理或者事实时，即使主句是过去时，从句也用一般现在时态。
例句：The teacher told us(that) nothing is difficult if we put our hearts into it.
老师告诉我们世上无难事,只怕有心人。
She said(that) her father is twenty-eight years older than her.
她说她父亲比她大二十八岁。
He said that light travels much faster than sound. 他说光比声音传播得快。
注意：当主句的谓语动词是think或believe，宾语从句要表达否定时，要把从句的否定转移到主句上。
I don't think he is going to help you with your English. 我认为他不会帮你学英语的。
这句话不可以翻译成：I think he isn't going to help you with your English.
如果宾语从句有它的补语时，宾语从句用it代替，从句后置。其句型为：主语+谓语+ it +补语+宾语从句。
I think it necessary that we learn English grammar.
我认为我们学习英语语法是必要的。
