Mary, I_____ John of his promise to help you．

I think he is taking an active part in social work. I agree with you ___________.

In the time of HINI, scientists ____ their spare time to conduct research on the ways of curing the disease.

When the bell rang, the students were all sitting on their own seats quietly and looking forward to        their new Chinese teacher.

 We should take exercise now and then. I believe we will ___________ it a lot.