It's necessary for students ______with their teachers．（ ）
A．communicateB．communicating
C．to communicate
It was for us to solve the math problem， few of us could even understand it．（ ）
| A． |
easy enough |
B． |
enough easy |
| C． |
difficult enough |
D． |
enough difficult |
There is a knock at the door． It my mom． It's time for her to be back home．（ ）
| A． |
may be |
B． |
may not be |
C． |
must be |
D． |
mustn't be |
The children here improve their English listening and speaking every day．（ ）
| A． |
on |
B． |
through |
C． |
with |
D． |
by |
Have you seen my mobile phone， Sam？ I can't find it ．（ ）
| A． |
everywhere |
B． |
somewhere |
C． |
nowhere |
D． |
anywhere |
While Mike computer games in his room， his dad came in．（ ）
| A． |
is playing |
B． |
was playing |
| C． |
will play |
D． |
plays |