In order to find the missing boy, the young couple            all they can over the past twenty-four hours. 
#101189
A
do
B
did
C
have been doing
D
had done
推荐题目
The gasoline _______. Let’s fill the car up at the next gas station.
#101070
A
is running out
B
has run out
C
is being run out
D
has been run out
— Isn’t it hard to drive downtown to work? —Yeah, that’s why I ______ to work by train. 
#101418
A
have gone
B
have been going
C
was going 
D
will have gone
Nobody but doctors and nurses and those ___________by Dr.Hu____________to enter the patient’s room.
#101622
A
invited; is forbidden
B
are invited; are forbidden
C
being invited; forbidden
D
invited; are forbidden