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
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Her sister left home in1998, and since.
#101660
A
had not been heard of
B
has not been heard of
C
had not heard of
D
has been heard of
Great changes ______ in my school in the past ten years.
#100927
A
took place
B
were taken place
C
have taken place
D
have been taken place
（2014年安徽省合肥市高三第三次教学质量检测）34. Neither the old lady nor her cats ______ out of the house since her husband passed away last month.
#99110
A
was stepping
B
have stepped
C
stepped
D
has stepped
—Why were you so late this morning? —I _____ in heavy traffic for an hour on the way here.
#101422
A
have been caught
B
have caught
C
had caught
D
was caught
— I have got a backache.— That’s not surprising. You ______ in front of that computer too long.
#100916
A
work
B
worked
C
have been working
D
are working