Nobody knows how people first came to these islands. They _____ from South America on rafts.
#87576
A
ust have sailed 
B
an sail 
C
ight have sailed
D
hould have sailed
推荐题目
—You didn’t invite Mary to the ball?—____ her, too? 
#89489
A
Must I invite
B
Should I have invited
C
Must I have invited
D
Should I invite
---John, how did your English exam go? -----I thought I ____,but in fact I came in the top 10% in the class.
#90317
A
should have failed
B
couldn’t have failed
C
might have failed
D
mustn’t have failed
The captain urged that the mission ________ before dark.
#87552
A
must be finished
B
be finished
C
ought to be finished
D
was finished