1. - What happened to him?
- he fell off the bike. He __ careful at firet.
A.should be B.must be
C.should have been D.must have been
答案为什么是选A而不是选B呢?
2.The teacher often tells us to help the students in trouble as ____ as possible.
答案为什么是填much 而不是many?
3.(1)The suggested answers are copied by the students.
(2)The new brige is being built。
为什么第一个句子的be动词后面没有进行时?而第二个句子后面就有呢?
4.Jim has made many friends since he ___ to china.
A.came B.comes
C.has come D.will come
为什么不是选B而是选A呢?
5.Everyone says the novel is worth ____ because it is very interesting.
为什么不可以填to be read呢?
6.mother told me ___ that I ___ back on time.
A.to be sure of; would come
B.to make sure; would come
答案选哪个? 为什么?