7.Although the causes of cancer ____， we do not yet have any practical way to prevent it.
#105343
A
are being uncovered
B
have been uncovering
C
are uncovering
D
have uncovered
推荐题目
—Why don't we choose that road to save time?—The bridge to it ________.
#105308
A
has repaired
B
is repaired
C
is being repaired
D
will be repaired
—Joan，what ________ in your hand?—Look！It's a birthday gift for my grandma.
#105314
A
had you held
B
are you holding
C
do you hold
D
will you hold
—I'm not finished with my dinner yet.—But our friends ________ for us.(2010·北京)
#105317
A
will wait
B
wait
C
have waited
D
are waiting
What shall we use for power when all the oil in the world has ?
#105323
A
given out
B
put out
C
held up
D
used up
一Ready to give up guessing，Sandy?一No，no，hold on! I think I______ at the answer now．
#105346
A
arrive
B
am arriving
C
have arrived
D
will arrive