1、As far as i know, Charles Babbage is generally considered_____the first computer.(A)
A.to have invented B.to invent
C.having invented D.inventing
2、He seldom,____makes mistaked in spelling.(C)
A.if B.even if C.if ever D.as if
3、You are doing well in your studies and make no trouble at home, but_____,you should know what sort of company you should keep.(D)
A.in spite it is true B.even if you are perfect
C.as it may be that D.be that as it may
4、After listening to us,he said only one of the plans_____him.(C）
A.affected B.touched C.impressed D.influenced
5、It is ridiculous that such a thing_____in your family.（B)
A.will happen B.should happen
C.would happen D.happened

1、consider to 是固定结构；be considered to 被认为，被当作
在不定式里，要表示一个过去的动作必须用完成结构。

2、这是一个省略现象，为了避免重复。原句应该是：
if he ever makes mistaken in spelling

3、插入语。“正如它可能的那样”

4、impress 及物动词作谓语，从句的时态要与主句的时态保持一致。

5、虚拟语气的一种。
It is ridiculous ( important, strange, impossible,ect.) + that ……(should ) do ……