(2013·重庆，23)It's not easy to change habits，________ with awareness and self－control，it is possible.
#30482
A
for
B
or
C
but
D
so
推荐题目
The new system needs to be in operation for five months ________ it can be updated.
#30274
A
as
B
while
C
before
D
once
Everything was placed exactly________he wanted it for the graduation ceremony.
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A
while
B
when
C
where
D
though
It was several years later________ an American ship paid the first official visit to the island.
#33589
A
since
B
when
C
that
D
as
Few people paid full attention to their health conditions ________ they were seriously ill.
#31465
A
when
B
if
C
until
D
after