(2010·辽宁高考)Doctors say that exercise is important for health, but it ________ be regular exercise.
#62385
A
can
B
will
C
must
D
may
推荐题目
—_______ do you clean your room?— Every day. 
#77537
A
How long
B
How many
C
How often
D
How soon
Jim has a _____. He is going to the USA to visit his sister.
#77041
A
two-months holiday
B
two months’ holidays
C
two-month holiday
D
two months holiday
A hot balloon blew up in Egypt. There ________ something wrong with the quality of it.
#62333
A
may have been
B
must be
C
need have been
D
might be