We were swimming in the lake _______ suddenly it began to rain heavily.
#30962
A
when
B
while
C
until
D
before
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The police said they would not give up looking into other possibilities ____they find out what happened.
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A
as
B
while
C
until
D
although
________ H7N9 is a deadly virus, it is still safe to eat thoroughlycooked chicken.
#30280
A
Until
B
While
C
If
D
Since
23. Tom had to be told two or three times ________ he could remember what the teacher said.
#79646
A
before
B
when
C
until
D
As