几道CET4的题目It was essential that the application forms----back

问题描述：

几道CET4的题目
It was essential that the application forms____back before the deadline.
A)must be sent
B)would be sent
C)be sent
D)were sent
选C
We____our breakfast when an old man came to the door.
A)just have had
B)have just had
C)just had
D)had just had
选D
The manager promised to keep me___of how our business was going on.
A)to be informed
B)on informing
C)informed
D)informing
选C
A new technique___, the yields as a whole increased by 20 percent.
A)working out
B)having worked out
C)having been worked out
D)to have been worked out
选C
请将每道题具体说明理由,谢谢

1个回答分类：英语 2014-11-23

问题解答：

我来补答

题目很简单,分析如下：
第一题,这里考的是虚拟预期.it is essencia that ……should be……是一般结构,当然,should 可以省略,因此,答案选择C.
第二题,过去完成时.这里主要考察时态,过去完成时表面在过去一点前已经完成的事情,结合题目意思,显然选择D；
第三题,考察keep的用法,keep sb informed of这里是个比较好的搭配,informed of总体做宾语补足语,其他词都不适合.因此,选择C.
第四题,主要考察语法知识.这是结合了时态和主动与被动的句子.由于前一分句和后一分句说的内容不一样,前面是说technique,而主语却是说的yield,因此,分词首先要考虑前面跟了什么,因此,首先排除D,因为没有这样的用法,如果用D,前面就不应该有technique.其次,就时态来说,用现在完成进行时态比较符合句子意思；最后注意到work out设计出,是个及物动词,因此technique需要用被动,因此答案选择C.

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