Question

几道大学英语选择题，望高手赐教，请说明原因。

1、 Having been asked to speak at the convention_____.
A. some notes were prepared for Dr. Smith.
B. Some notes were prepared by Dr. Smith
C. The convention members were pleased to hear Dr. Smith
D. Smith prepared some notes

2、It is desirable that he ____.
A. gives up trying
B. give up trying
C. would give up trying
D. is going to give up trying

Answer 1

1 D having been asked是完成加被动的结构，独立做状语，表示这个动作在主句的动作之前发生，那么主句的主语就应该能够发出speak这个动作，比较一下四个选项的主语就可以看出来，只有D答案的主语是人，能够speak

2 B 虚拟语气的用法
出现desire和desirable的句子，宾语从句或表语从句中都用should do这个形式做谓语，should可以省略

Answer 2

D
前面一句的主语省略了，但是明显是Smith

B
it is +adj(一类特定的形容词，表达愿望、要求等)＋that 从句

这个结构中，从句为虚拟语气，谓语动词要用原形

Answer 3

D
前面的独立主格结构没有自己的主语，所以应该和主句主语一致，都是Smith

C
虚拟。如果他放弃努力的话是让人满意的结果。

Answer 4

1d 主谓一致，是smith 被ask
2that- clause省略" should”表示建议，虚拟语气