With the help of high technology, more and more new substances ___in the past few years.
#101737
A
discovered
B
have discovered
C
had been discovered
D
have been discovered
推荐题目
I had meant to meet you at the airport this morning but I was too busy for I_______ a report.
#100524
A
wrote
B
was writing
C
have written
D
had written
---What’s that unpleasant noise?---Oh, the road before the main gate ______.
#99995
A
is repairing
B
is being repaired
C
is repaired
D
has been repaired
I _____ of your trying to earn some money by taking part time jobs, but please don’t neglect your studies at university.
#99300
A
assess
B
acquire
C
appreciate
D
approve
He doesn’t know the city very well, because this is the first time he _______ here.
#102302
A
came
B
has been
C
come
D
am coming
---The window is dirty.----I know. It ______ for weeks.
#101155
A
hasn’t cleaned
B
didn’t clean
C
wasn’t cleaned
D
hasn’t been cleaned