问题

When the teacher came into the classroom, the students ____ in groups.
A:work
B:have worked
C:were working
D:are working
B:have worked
C:were working
D:are working
正确答案是:
同类题型
What’s _____most useful invention in the 20th century? —_____ computer, I think.
Which of these shirts do you like best?— I’ll take. They are all expensive and out of fashion.
Our teachers think Jim the best student. The sentence structure is _______