Although the causes of cancer_____, we do not yet have any practical way to prevent it.
#104936
A
are being uncovered
B
have been uncovering
C
are uncovering
D
have uncovered
推荐题目
We had thought Carla would say a lot about her job interview, but she ____ it.
#101891
A
doesn’t mention
B
didn’t mention
C
hasn’t mentioned
D
hadn’t mentioned
All of the guests by 9 o’clock , but the host until 15 minutes later .
#104838
A
arrived ; didn’t turn up
B
had arrived ; didn’t turn up
C
arrived ; hadn’t turned up
D
had arrived; hadn’t turned up
My parents have promised to come to see me before I _________ for Africa.
#101964
A
have left
B
leave
C
left
D
will leave
—What were you doing when she dropped in? —I for a while and_________ some reading.
#104243
A
was playing; was going to do
B
played; did
C
had played; was going to do
D
had played; did
----Is this the first time you ________ to Harbin?---- No, but the first time I ____ here, the city wasn’t so beautiful.
#102687
A
visited; came
B
visited; have come
C
have visited; have come
D
have come; came