3.---I haven`t heard from Henry for a long time.

3.---I haven`t heard from Henry for a long time.
---What do you suppose___C____to him.
A.was happening B.to happen
C.has happened D.had happened
10.Do you know the difficulty he had ____C____the work?
A.finished B.to finish C.finishing D.having finished
11.We`ll have to finish the job,_____D____.
A.long it takes however B.it takes however long
C.long however it takes D.however long it takes
15.Only three books are borrowed,the rest____B____all mine.
A.is B.are C.have been D.has been
16.---Which of the two computer games did you prefer?
---Actually I didn`t like____B_____.
A.both of them B.either of them C.none of them D.neither of them
17.The speaker raised his voice but still could`t make himself___C____.
A.hear B.hearing C.heard D.to hear
18.He told me that Mr.Smith was the man___A____he believed could be trusted.
A.who B.whom C.which D.不填
19.In our class,three students___B___ten practice_______English everyday.
A.in;read B.in;reading C.out of;to read D.out;reading
20.___D____from the root of the mountain,the palace looks more magnificent_________the blue sky
A.Seeing;under B.To see;against C.Saw;over D.Seen;against
25.The number of the students____C____fallen________70% this year.
A.have;by B.have;at C.has;by D.has;at
请各位能够为我分别解释这些题为什么要这样做,最好能写出各个所考察的语法点,打得好追加分.

3.C
do you suppose是插入语,只影响句序,做题时可以先去掉.答语就变成了：What ___ to him?What是该句的主语,happen是谓语,排除B；再根据上文时态对应,答语也应该采用现在完成时.
10.C
此题先是一个定语从句,关系代词（which/that）代替先行词the difficulty做had的宾语,所以关系代词被省略.
再看定语从句,它含有一个固定结构：某人做某事有困难,即：
he had difficulty with sth或he had difficulty （in）doing sth.
11.D
no matter引导一个让步状语从句即：no matter how long it takes“不管它花多久时间”,而no matter how=however.
15.B
the rest做句子主语时,动词的单复数形式应该与它所代替的事物性质保持一致.很明显此处the rest=the other books（由all也能看出是三者以上）,故动词用复数,排除AD；再根据前句时态,选B.
16.B
根据题意,说者对两个游戏中任意一个都不喜欢（全部否定）.none指三者及以上,排除；答句已经有了否定,不能否否得正,排除D；而both和not连用,是部分否定（指对这两本书不都喜欢,但喜欢其中一本）,而非全部否定,排除.
17.C
此题很简单,the speaker提高音量是为了使自己（声音）被别人听见,himself和hear之间是被动关系：使役动词make+宾语himself+宾语补足语heard(Vpp).
18.A
定语从句中又插入了一个插入语,同第1题,先去掉此插入语.该选项为关系代词,它要代替先行词the man做定语从句中could be trusted的主语,指人且做主语,当然用who并不能省略.
19.B
固定短语：three students out of ten或three students in ten,意思是“十个学生里面就有三个（学生）”,排除D；
又是一个固定短语：practice/practise (doing) sth “练习（做）某事”.
20.D
根据一点就可以做出该题.此句第一横线该填入动词的非谓语形式做状语,而该动词的主语是th palace,当然是它“被看”,被动所以用过去分词.agianst表示一种“映衬,对比”之意.
25.C
the number of...意思是“...的数量”,该主语视为单数,动词也用单数形式,排除AB；“减少了70%”用fall by 70%,“减少到70%”用fall to 70%,但不存在用at的用法.