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
推荐题目
we go there by train or by ship makes no difference．The time and the fees are the same．
#33137
A
Which
B
How
C
Whether
D
Why
I should convey my appreciation to my high school teachers, without ____ help I wouldn’t achieve such a big success.
#33344
A
whom
B
them
C
which
D
whose
—Was it there _______ you were away to answer the phone? —There is no doubt about it.
#33929
A
that
B
which
C
while
D
where
______ there is a snowstorm or other bad weather ,the bus always comes on time.
#79889
A
Because
B
if
C
When
D
Unless