1.C(however然而,可是,意为他从没在欧洲旅行过,可是(除了)他有一次刚去到巴黎就回来了.that is to say/namely是即,换言之的意思)
2.D(want to read)
3.B(I had planned to go to London是虚拟语气,意为我原本打算去伦敦,但是我付不起车票钱)
4.B(warn常与of、against连用)
5.A(虚拟语气but that he came to help me=If he had not come to help me,I could not have done.)
6.A
7.A(no sooner...than..)
8.A(what=all that)
9.A(allow somebody to do)
10.C
11.D(虚拟语气,what would you tell her是针对将来时的虚拟语气,所以条件句要用针对现在时的虚拟语气即过去时.)
12.A(注意主句中的now,针对现在的虚拟语气用过去时would/could/should+动词原形)
13.D
14.D(had better not do)
15.B(表示到那时用by)
希望对你有帮助.