1．Earth is a rocky planet where there is liquid water，which is necessary for life to ________.
A．exist B．come C．stand D．happen
2．He ________ and his T-shirt became too small.
A．lose weight B．put on weight C．cut down fat D．earned his living
3．We must ________ the act of cheating ________ a fair competition system.
A．prevent; creating B．stop; creating C．keep; from creating D． stop; to create
4．________ Mr.Smith is well again，he can go on with his work.
A．Now and then B．Now that C．The other day D．Now just
5．I had no idea when World War Ⅱ________，so I turned to my teacher for help.
A．broke down B．broke in C．broke out D．broke away
6．—May I open the window to let in some fresh air?
—________
A. Come on! B. Take care! C. Go ahead! D. Hold on!
