Garbage sorting （垃圾分类） encourages people to live_____ life than before． It makes the earth a better place to live in．（ ）
| A． |
a greener |
B． |
the greenest |
| C． |
a wilder |
D． |
the wildest |
Is tom coming by train？He ______drive his car，I'm not sure．（ ）
A．can'tB．mayC．must
_______ Children's Day，all the children are very happy．（ ）
A．toB．InC．On
What were you doing when I phoned you yesterday evening？
I _______ my homework．（ ）
A．was doingB．have doneC．did
Fifty yuan ________ enough．（ ）
A．isB．amC．are
My teacher asked me ________ the room．（ ）
A．cleanB．cleansC．to clean