(2013·宁夏银川一中高三第四次考试)________ scores of times, but he still couldn't understand it.
#30539
A
Having explained
B
Having been explained
C
Though it was explained
D
It was explained
推荐题目
—How long do you think it will be______ man can finally solve the problem of cancer?—Well，it depends
#30976
A
when
B
until
C
after
D
before
_____ computers are convenient to us in daily life, it may also cause other problems.
#33235
A
Whether
B
Because
C
As
D
While
The two military exercises were similar __________ they were both intended to give a threat to a certain country.
#31922
A
to what
B
for which
C
in that
D
except that
Scientists say it may be five years ______ it is possible to test this medicine on human patients．
#31988
A
since
B
until
C
before
D
when