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
Since the band announced the release of their new album, the phone hasn't stopped ringing. Many fans ________ to ask about the exact time.
#105307
A
were calling
B
had called
C
are calling
D
call
— ________ for the glass! —It’s OK. I’m wearing shoes.
#105336
A
Look out
B
Walk out
C
Go out
D
get out
Hurry up，kids！The school bus ________for us！ (2013·四川，3)
#105306
A
waits
B
was waiting
C
waited
D
is waiting