11. The course normally attracts 20 students per year, ___ up to half will be from overseas.
A) in which B) for which C) with which D) of whom &nbs p;
12. A survey was carried out on the death rate of new-born babies in that region, ___ were surprising.
A) as results B) which results C) the results of it D) the results of which
13. He came back late, ___ which time all the guests have already left.
A) at B) after C) by D) during
14. I hope all the precautions against air pollution ____ suggested by local government will be seriously considered here.
A)as B) while C) after D) since
15. I've never been to Beijing, but it is the place ___.
A)that I want to visit it most B) where I'd like to visit
C) in which I'd like to visit D) I most want to visit

语法参考答案
11. D) 题意：这门课程通常每年招收20名学生，其中多大半数的学生来自海外。
解析：本题的测试点是介词的用法和介词+which/whom引导的定语从句。Up to half和whom指代的先行词students之间是所属关系，故应为of whom。
12. D) 题意：那一地区新生儿死亡率的调查结果令人吃惊。
解析：同题10。
13. C) 题意：他回来很晚，回来时所有的客人都已经走了。
解析：本题的测试点是介词的用法和介词+which/whom引导的定语从句。由从句的现在完成时时态可判断此处的时间引导词应为by。
14. A) 题意：我希望当地政府将严肃考虑提出预防这儿空气污染的所有措施。
解析：此句为省略从句助动词are的非限定性定语从句。
15. D) 题意：我从未去过北京，但它是我最想参观的地方。
解析：此句的先行词虽为指地点的place，但定语从句中缺宾语，且visit是及物动词，故只能选A。