The professor devoted all his life ____the treatment of AIDS.A to research B.in researching C.to researching D.at researching
Igot caught in the rain and my suit___
___to reach them on the phone,we sent an email instead
You should___your parents’ approval before you go to camp with us
He has a habit of keeping his arms___when talking to others,which___impolite to his audience
The questions listed here are just a few problems that teenagers may___