The final tests are coming, and the students _______ hard for them these days.

The climate is changeable in this area. You should prepare more clothes ___________ the sudden change of weather.

I wonder if he_____us, and I think if he_____us we’ll be able to complete the task ahead of time

李明同学说话喜欢引经据典，在下面几种情境讲话时，他引用的古诗文恰当得体的一项是（ ）

How many students are there in the classroom— . They are all in the lab.