Fighting an artificial greenhouse effect seems to be the greatest of environmental challenges, ________？
#64479
A
isn't it
B
does it
C
doesn't it
D
is it
推荐题目
-----Alice, you clean the blackboard today, _________?----- But I cleaned it yesterday.
#64603
A
won’t you
B
will you
C
didn’t you
D
don’t you
—Alice, you feed the bird today；______ ？ —But I fed it yesterday.
#65414
A
do you
B
will you
C
didn’t you
D
don’t you