16. Whenever we hear of a natural disaster, even in a distant part of the world,

                   a                         b

we feel sympathy for the people having affected.

            c                          d

答案：  D

解析：  人被（灾难）所影响，应该用被动语态，应改为: having been affected.

17. Mary said her mother would buy her a five-speeds racing bicycle for her sixteenth

                           a              b                     c         d

birthday.

答案：  B

解析：  有短横线连接的形容词不用复数形式，应该改为five-speed.

18. I have lost so much weight recently so all my clothes are too big; I must have

                          a             b                               c

them taken in.

d

答案：　B

解析：　改为：that.

19. Even though he had been studying English for three years before he came to        a                b                                   c

England, it is still difficult for him to make himself understand.

d

答案：　D

解析：　尽管他在去英国之前已经学了三年的英语了，但要别人明白他依然是有困难的。这里他是被人听懂，理解的，所以要用被动语态，故D项改为： understood.

20. His paper contains less mistakes than ours.

       a              b             c    d

答案：  B

解析： B项改为：fewer;  因为less修饰不可数名词, 而修饰可数名词应该用：fewer, 用比较级，因为后面用than, 有比较对象.