在定语从句中引导地点用that 和where的区别
1.看被定语从句所修饰的先行词（名词/代词）能不能直接和从句相连.
如果可以直接和从句其他成分相连,无须补上介词,则用that/which；
如果需要额外补上介词才能放在定语从句中,则用where.
如：This is the city (which/that I stayed in last year).
把先行词the city放入后面的定语从句,为：
I stayed in (the city) last year.
the city直接做介词in的宾语,所以用which/that.
再如：This is the city (where I stayed last year).
把先行词the city放入定语从句,需要补上介词in方可,即为：
I stayed (in the city) last year.
所以使用where或in which.
2.看定语从句是缺少地点状语还是缺少主语/宾语/表语.
如果缺少地点状语,用where；
如果只缺少主语/宾语/表语,则用which/that.
如：This is the city (which/that) I visited last year.
从句I visited last year中,及物动词visited后面缺少一个宾语,所以用which/that；
再如：This is the city (where) I lived last year.
I lived last year中,缺少地点状语in the city,所以用where或in which
situation后面的定语从句用that还是where
简单地说，situation后接的'定语从句到底该用that, which来引导还是用where来引导，主要看后面的定语从句的主谓宾是否完整：
1.如果定语从句的主谓宾是完整的（不缺主语也不缺宾语），则要用where来引导。如：
It is asituation wherebasic human rights are being flagrantly abused.这种情形是对基本人权的公然践踏。
If you risk something important, you cause it to be in a dangeroussituation whereyou might lose it.你如果拿重要的东西去冒险，那你就是将它置于一种可能会失去它的危险境地。
It’s helpful to put children in asituation wherethey can see themselves differently.把孩子们放到一个能够让他们从不同角度看待自己的环境中，这对于他们会有所帮助。(2009福建卷高考题)
2.如果定语从句的主谓宾不完整（比如缺少主语或者缺少宾语），则要用that, which来引导。如：
It’s asituation thatmust be dealt with.这是必须要处理的事情。
This is asituation whichcannot be changed.这是无法改变的事实。