关于that和where,什么时候该用哪个?怎样判断是否强调和where引导的定语从句?或者什么什么

1.定语从句中,如果它缺少地点状语,则需要填入关系副词where.
如：This is the city where I stayed last year.
或者可以说：如果将被定语从句所修饰的名词（即先行词）放入定语从句中,如果不能直接相连,需要借助于介词时,则填入关系副词.
即不能说：I stayed (the city) last year.
而必须说：I stayed (in the city) last year.
同理,定语从句中缺少主语/宾语/表语时,则需要填入关系代词which/that.
如：This is the city which/that I visited last year.
或者可以说：如果将被定语从句所修饰的名词（即先行词）放入定语从句中,如果可以直接相连时,则填入关系代词.
即可以直接说：I visited (the city) last year.
而且有一个固定公式：关系副词 = 介词 + 关系代词 = 介词 + 先行词
例句中即：where = in which = in the city
2.而强调句型中,使用的引导词只能是who/whom/that,其中that是万能的,可以用在所有的强调句型中.
而where是绝对不能用作强调句型的引导词的.
强调句型的结构是死板的：It is/was + 被强调部分 + that + 句子未被强调部分.如果被强调部分为句子表人的名词/代词,则可以将that换成who/whom.
3.如果句子结构不是上述结构,则肯定不是强调句型.
同样,如果出现类似结构,但是引导词不是who/whom/that,则也肯定不是强调句型.
4.而且,强调句型有一个最大的特点：如果将It is/was和引导词who/whom/that去掉之后,剩下部分刚好是完整的原句（有时候需要调整句序）.
5.楼主所提供的句子为定语从句.其中where = at/in which = at/in a good place.
如果要把你的例句变成强调句型,则必须是：
It is at/in a good place that we can prepare ourselves well for the future.
去掉It is和that之后,则原句为：
We can prepare ourselves well for the future at/in a good place.