________ Mary ________ Jack is listening to the report carefully, because they are both interested in it very much.

      caused the accident is still a complete mystery.

—Can I ask you a few straightforward questions about yourself?—No problem. I like ________ when people are open and direct.

All of the doctors have worked for a long time, but ________ of them stop to have a rest.

-----How many students are there in the classroom?------_______.