There ________ something wrong with my mobile phone． It can't work these days．（ ）
| A． |
must be |
B． |
can't be |
C． |
may be |
To live a low﹣carbon life， we must remember ____ the lights when we leave the room．（ ）
| A． |
to turn off |
| B． |
turning off |
| C． |
not to turn off |
Wang Yangming is a great educationalist _____ developed most of his thoughts in Xiuwen．（ ）
| A． |
which |
B． |
What |
C． |
who |
Volunteering _____ the world warmer． Even small things can make a big difference．（ ）
| A． |
make |
B． |
makes |
C． |
was making |
The People's Republic of China was founded ____ October 1st， 1949． We'll celebrate its 70th anniversary this year．（ ）
| A． |
in |
B． |
on |
C． |
at |
Dad， my bike is broken．____I use yours？
Sure! It's in the backyard．（ ）
| A． |
Must |
B． |
Should |
C． |
May |