英文问题
1、In the centre of Shanghai,there is a library _____students often go to read newspapers and magazines.
A.to which B.by which C.in which D.of which
(请说明答案及理由，并讲解一下这四个答案的区别）
2、_____the meeting, he would have attend.
A.If he knew B.If he hadn't known
C.Had he known D.If he didn't know
(请说明答案及理由）
3、That place is worth____hundreds of miles to visit.
A. to travel B.travel C.travelled D.travelling
(先把句子解释一遍，再说明答案及理由）
参考答案:A.非限定性定语从句，答案中的to其实是后面go的搭配，而题干中给的go后面的to只是表目的的结构词，和其他几个的区别就是其他的是错的，只能用这个。
A.主句是表示与过去事实相反的虚拟语气，从句用一般过去语态。
D.那个地方值得不远万里的前去参观。be worthy doing 值得做某事。