Time waits for no man. But some people won't realize the importance of time______it's gone.( )
A.asB.sinceC.whenD.until
Mr. Black walked around and offered help____we were doing an experiment.( )
while
although
until
unless.
Michael_________in a school in Yunnan from February to June next year.( )
teach
taught
will teach
was teaching
Must I do the project on my own?
No, you____.You can work with your classmates.( )
needn't
can't
shouldn't
mustn't
Frank is an independent boy. His parents are proud ____ him.( )
on
to
in
of
The bridge between the two islands is _______ one in Shanghai.( )
long
longer
longest
the longest