1.He helped his father in the small town( )they lived.2.That

1.定语从句,they lived [in] the small town,缺少介词.用CF.
2.定语从句,we visited the museum,不缺介词.用AB.
3.定语从句,we paid a visit [to] the factory ,缺少介词,用E.
不知老师有没有系统讲过定语从句呢?系统学习一下应该会好些的.
PS：关系副词
when=at\in\on\during（等等） which 代替表时间的名词
where=in\at\to（等等） which代替地点
why=for which代替reason