He could not guess how they managed ______. A: A.doing this B: B.to doing this C: C.to do this D: D.to doing this

The questions is _____. A: whether is it worth doing B: that if it is worth doing C: whether it is worth doing D: if it is worth doing

The teacher, together with his five students, _______ a new experiment ___________ the office. A: is doing; in B: are doing; in C: are doing; on D: is doing; on

I __________ doing something __________ doing nothing.

Can you imagine _________? A: what his doing B: What is he doing C: what he is doing D: he is doing what

Nobody knew what this guy ______ all these years. A: had been doing B: have being doing C: was doing D: has been doing

What ___ he ___with our parents? A: do;doing B: does;doing C: is;doing D: is;do

He was busy ____ his homework. A: doing B: to do C: that he was doing D: he was doing

What you this time tomorrow? A: ore; doing B: are; be doing C: wil; do D: will; be doing

We __________ (do) some cleaning at that time. A: did B: did doing C: were doing D: are doing