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
The College Entrance Examination________near, so you should be prepared for it.
#105333
A
is drawing
B
draws
C
drew
D
has drawn
6.I have to go to work by taxi because my car ____at the garage.
#105344
A
will be repaired
B
is repaired
C
is being repaired
D
has been repaired
Hurry up，kids！The school bus ________for us！ (2013·四川，3)
#105306
A
waits
B
was waiting
C
waited
D
is waiting
--- Would you care for a cup of coffee? --- I ________ one. Thank you just the same.
#105330
A
had
B
have had
C
would have
D
will have
“The moment ________ soon”，he thought to himself，waiting nervously.(2012·湖南)
#105316
A
came
B
has come
C
was coming
D
is coming