I don’t know how ________ commas. 
#69179
A
use
B
using
C
used
D
to use
推荐题目
-- What’s the time now? --- 8:00 a.m. It’s time ___________.
#70654
A
get up
B
for class
C
for bed
D
to have lunch
__ is really hard __ them to climb Mount Tai. 
#69186
A
This, to
B
It, to
C
This, for
D
It, for
His sister has a bad cough,  ____________ she?
#71024
A
wasn’t
B
doesn’t
C
hasn’t
D
does