Question

状语从句什么时候加where什么时候不加where？

Answer 1

状语从句可表示时间、地点、原因、条件、让步、方式、比较、目的和结果等意义。不同的状语从句要求用不同的从属连词或相当于从属连词的词组引出。其中地点状语从句用连接词where，wherever或everywhere引出，详细如下：
时间 when, while, as, as soon as, before, after, since, till, until, the moment, directly, once, immediately
地点 where, wherever, everywhere
原因 because, as, since, now (that), seeing (that), in that, considering (that)
条件 if, unless, as (so) long as, on condition that, provided/providing that, suppose, in case
让步 though, although, even if, even though, as, whether no matter (what, when, who ...), whatever (whenever, whoever...)
方式 as, as if, as though, the way
比较 than, (not) as ... as, not so … as, the…. the…
目的 that, so that, in order that, lest, in case, for fear that
结果 so that, so …that, such ... that

Answer 2

状语从句加where 构成地点状语从句，如: Let's meet where the two roads join,shall we? (我们在两条路交汇处碰头好吗？)
状语从句除了地点状语从句处还有时间、原因、条件等从句，它们都不加where。

Answer 3

where是问"在哪儿"的疑问词，问地点，引起特殊疑问句，宾语从句，主语从句及表语从句。状语从句没加where的，当where+ever时，可引导让步状从或宾语从句。

Answer 4

从句中不含介词(比如at、in、on等一些后面可以接地点的介词)要用where(相当于介词+which)，从句含介词的话就不用where用which了。