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.
《初中英语语法 宾语从句中的三关》由英语编辑整理,更多请访问:https://www.liuxue86.com/english/