1. 引导词关

如果从句是陈述句，引导词用that(that在口语或非正式文体中常省略);如果从句是一般疑问句，引导词用if/whether;如果从句是特殊疑问句，引导词用由疑问词转换而来的疑问代词/副词。

2. 语序关

①陈述句变为宾语从句，语序不变，即仍用陈述语序。如：

He is an honest boy. The teacher said. →The teacher said(that)he was an honest boy.

②一般疑问句和特殊疑问句变为宾语从句，语序变为陈述语序。如：

Does he work hard?I wonder.→I wonder if/whether he works hard.

When did he leave?I don’t know. →I don’t know when he left.

3. 时态关

①如果主句是现在的时态，从句的时态可根据实际情况而定。如：

I have heard(that)he will come back next week.

②如果主句是过去的某种时态，那么从句的时态一定要用过去的某种时态。如：

He said(that)there were no classes yesterday.

注意：如果宾语从句表述的是客观真理、自然现象等时，不管主句是什么时态，从句都要用一般现在时。如：

He said that light travels much faster than sound.