It's necessary for you _______the classroom clean，class．（ ）
A．keepB．keepingC．to keep
Did you hear someone knock at the door just now？
Sorry．I ______ to my friend on the phone．（ ）
| A． |
was talking |
| B． |
talked |
| C． |
am talking |
A kind of shared bike ______ is called bluegogo is getting more and more popular in Chengdu．（ ）
| A． |
it |
B． |
who |
C． |
which |
Jim studies better than Tom，but Tom is _______ and he has more friends．（ ）
| A． |
friendly |
| B． |
more friendly |
| C． |
the most friendly |
Many people still try to climb Qomolangma every year _______ it is very dangerous．（ ）
| A． |
when |
B． |
if |
C． |
though |
This pair of glasses ______ be Tony's．He's the only one who wears glasses．（ ）
| A． |
must |
B． |
might |
C． |
can't |