一句定语从句的问题，急急急

首先，要看引导词在定语从句中做什么成分：主语、宾语还是状语，或者说从句缺什么成分。如果是主语或者宾语就用that,如果是状语就用where或者when.
It is the village that I visted last year.(that 做visit的宾语）
It is the village where I lived last year.(live是不及物动词，不需要宾语，从句的主语也有了，所以从句的引导词应该用where或者when这类可以做状语的.这时再看先行词是表示时间还是地点。在此句中是village（地点），所以用where.

in which
this is the factory that Tom works in

定语从句中where = in which

我是英语专业的，肯定没错。

where~~=which/that Tom worked in

定语从句中，指代没有加介词的地点时，用where
如果地点前已有介词，则用which (介词+which=where），而不能用that

此句中：是tom works in the factory，所以当没有in时，用where指代factory
也可说this is the factory in which tom works，

这个地方要注意咯，factory ,是地点，所以要用where ,这里的where 就是等于in which .
后面where Tome works 就是来修饰factory的。

in which 等于 where