判断是否定语从句,要看有没有先行词.之所以叫做定语从句,是因为引导词引导的定语从句是作先行词的定语结构的.
-When and where you get to know her?
-It was on the farm( )we visited.
上面这个句子中,which引导定语从句,是修饰先行词farm的.这里不能用where是因为从句缺少宾语,而where不能作宾语（名词结构）.如果该句改为It was on the farm ( ) we meet.这里就可以用where了.
至于第一句The church was built( )a Roman temple had dnce been locate.根据我上面的解释,没有先行词,如果是in which,which指代什么?如果该句改为The church was built on the hill ( ) a Roman temple had dnce been locate.这里就可以用on which了.
You got it?