Mike's mother sent a letter to Mike. He signed for it ________ person this morning.
I'm so sorry to take your book ________. Here you are.
A.by bike B.by mistake C.by chance D.by accident
We don't know why Tom is so worried. It's not his problem________．
A.in person B.after all C.thanks to D.at least
Jerry is _________ today. He needs to clean the blackboard and the classroom.
A.on duty B.on fire C.on business D.on sale
This is the best thing you've ever done. I'm so happy f________ you.
Please don't drink plenty of cold water a________ doing sports. It's bad for your health.
