1.—The duty of Project Hope is to help poor children,isn't i

1.—The duty of Project Hope is to help poor children,isn't it?
—Yes,it has built many schools _____those children can study happily.
A.where B.when C.which （这道题选A,希望可以顺便说一下which与where在定语从句中的区别,
2.The question is not easy ______.
A.answer B.to answer C.answering D.to be answered
(此题正确答案是B,为何不选D?)
3.I wonder__________
A.who broke the window B.who the window broke
C.whose coat is this D.what is the population of China
(此题正确答案是A,讲下原因,
4.By the school____over ,the rain ____,so I didn't use my raincoat.
A.was,had stopped B.had been,had stopped
讲下原因,

1.which和where的区别就是关系代词和关系副词的区别.
1）关系代词which可以直接换成先行词（即为定语从句所修饰的名词/代词）,然后放入定语从句,并在定语从句中充当代词所能充当的成分,比如主语/宾语/表语.
如：This is the city (which I visited last year).
关系代词which代替先行词the city,并在定语从句中充当visited的宾语.
2）关系副词where相当于“介词+先行词”,然后一起放入定语从句中去,并充当从句中的地点状语.
如：This is the city (where I lived last year).
where=in + the city,做定语从句动作I lived的地点状语.
两者区别关键在于：
如果把先行词（必须是名词/代词）直接放入定语从句中去,如果（需要再加上某介词后再一起）做从句的地点状语,则用关系副词where；反之,先行词可以直接放入定语从句中做名词性成分（主语/宾语/表语等）时,则直接使用关系代词即可.
3）以此题为例,先行词是many schools,放入定语从句后,只能再在其前补上介词in,然后一起做从句的地点状语.即完整的定语从句为：
Those children can study (in many schools) happily.
所以用where=介词in + 先行词 many school(可以用which来代).
最后,给楼主一个常用公式：关系副词=介词+关系代词(先行词）.
2.该题考察一个常用的用主动表示被动的句型:
Sth/Sb be adj to Vt (Vi+介词).=It be adj to Vt (Vi+介词).
本题The question is not easy to answer.=It is not easy to answer the question.
再如:The man is hard to work with.=It is hard to work with the man.
注意:此句型要求用主动语态,尽管中文意思上其表达的是被动关系.
3.这道题考查宾语从句的语序问题.如果宾语从句是个特殊疑问句,则从句采用“疑问词+陈述句序（即主谓宾的正常顺序）”的结构来表达.
如：How old are you?→I don't know how old you are.
再来看本题的四个答案：
A who broke the window
刚好who就是充当句子的主语,宾语从句符合“疑问词+陈述句序”的结构；
B.who the window broke
谓语broke居然放在宾语the window后面,不是陈述句序；
C.whose coat is this 应该改为：whose coat this is才符合疑问词+陈述句序”的结构；
D.what is the population of China 应该改成：what the population of China is才符合“疑问词+陈述句序”的结构.
4.正确答案是A.
翻译：等到放学时,雨已经停了,所以我没用到我的雨衣.
“雨停了”这个动作在“放学”这个动作发生时就已经发生了,所以两个都发生在过去的动作强调了先后.很明显发生更早的动作用过去完成时,更后的动作用一般过去时.