The central heating system of this office building is down and several workers ______ it right now.
#99933
A
had repaired
B
have repaired
C
repaired
D
are repairing
推荐题目
You may not have played very well today,but at least you’ve got through to the next round and _______.
#104616
A
tomorrow never comes
B
tomorrow is another day
C
never put off till tomorrow
D
there is no tomorrow
I ______ the TV series The Legend of Zhenhuan when my mom made a phone call to me.
#100888
A
am watching
B
watching
C
was watching
D
was watched
Ladies and gentlemen, please fasten your seat belt. The plane __________. 
#102320
A
takes off
B
is taking off
C
has taken off
D
took off