(2013·高考北京卷)Don’t turn off the computer before closing all programs，________you could have problems.
#30670
A
or
B
and
C
but
D
so
推荐题目
Children’s brains cannot develop properly _________ they lack protein.
#30134
A
because
B
since
C
when
D
unless
—____when has the country been open to international trade?—1978,I suppose.
#79800
A
Since
B
In
C
From
D
After
I have watched a number of movies recently,______ none of them have impressed me．
#30136
A
but
B
or
C
so
D
for
She’ll never forget her stay there ______ she found her son who had gone missing two years before.
#32659
A
that
B
which
C
where
D
when