问题
We can gain valuable wisdom from mistakes which ______ to prevent them from happening again.
A:should be avoided
B:might be avoided
C:must have been avoided
D:could have been avoided;
B:might be avoided
C:must have been avoided
D:could have been avoided;
正确答案是：
同类题型
Entry in this competition is restricted________high school students.[ ]
a, __________ the alarm clock for 6 o’clock, oryou will oversleep and be late for the train
When you go _________ the street, you must be careful.
u know our town at all —– No, this is the first time I ______ here.
Susan, why are you still here They are all ready to start. —I’m sorry, but I _____when to meet.