Scientists say it will be five or six years __________ it is possible to test this medicine on humans.
#30743
A
after
B
before
C
since
D
when
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John thinks it won’t be long _________ he finishes the tough work.
#31516
A
when
B
after
C
since
D
before
All the guests at the party were dancing and singing happily _____ the electricity was cut off.
#30392
A
until
B
while
C
when
D
because
Air pollution is getting more and more serious, so we must take action it is too late.
#31510
A
before
B
after
C
until
D
when
28. John may come to see me tonight. I can’t go to the movie with you______he visits.
#79686
A
as long as
B
in order that
C
because
D
in case
Tom is good a student he is often praised by the teacher.
#30357
A
such; as
B
so; as
C
such; that
D
so; that