宾语从句简单说一下是什么结构

复合句中用句子作宾语叫做宾语从句。
1 引导词
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
①陈述句变为宾语从句，语序不变，即仍用陈述语序。
He is an honest boy. The teacher said.
→The teacher said (that) he was an honest boy.老师说他是一个诚实的男孩。
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。
When did he leave? I don't know.→I don't knowwhen he left.我不知道他什么时候离开的。
Does he work hard? I wonder.→I wonderif/whether he works hard.我想知道他是不是工作努力。
3 时态
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。
I have heard (that) he will come back nextweek.我已经听说他下周回来。
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。
He said (that) there were no classesyesterday.他说昨天没上课。
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。
He said that light travels much faster thansound.他说光速比声音快多了。