4.B when先行词是the end of 2004
5.D who( I think) has something...括号内是插入语
6.C such...as...引导的定语从句
7.B case 之后的定语从句必须由 where/in which 引导
8.A by which thime 到那时
9.B 引导非限制性定语从句的which 不能省.
10.B when= one more week
11 B whether ...or...follow one advice 听从某人的建议
12.A 用还原法：it takes what to do...
13.D what 做made 的主语； that 引导表语从句,在从句中不充当成分.
14.A who is known as..是表语从句.
15.C 引导表语从句,在从句中充当地点状语
16.B 所有从句都用陈述语序
17.C 还原法 I could have done what with...
18.C what 做fear 的宾语
19.B it 形式宾语,真宾 是if ...