When something is on fire, people throw sand on it to put out the fire. The main use of the sand is to _________. 
#54333
A
protect the thing on fire
B
add weigh to the thing on fire
C
keep the air away from the thing on fire
D
lower the temperature of the thing on fire
推荐题目
Li Ming is in poor health. He should pay more attention _________ exercise. 
#57164
A
to take
B
to taking
C
for taking
D
in taking
- Claudia, are you going to Jeff’s birthday party on Saturday?-Unless I______ .
#52633
A
will be invited
B
am invited
C
was inviting
D
invited
 Turn off the water while you ________ your teeth or washing your hands.
#52150
A
were brushing
B
brush
C
are brushing
D
brushed
What would you do if you ________ on the moon? 
#53043
A
live
B
lived
C
have lives
D
will live