________you never plan to visit the polar bears in the North Pole or the penguins in the South Pole，now it is the proper time to start thinking about that.
#30102
A
Until
B
Unless
C
As long as
D
Even if
推荐题目
The old man lost his money and he has been worried ________.
#33629
A
even if
B
even as
C
ever since
D
as if
_____ is known to us all is that to work hard to achieve a goal is more important than only to have a goal.
#33807
A
What
B
As
C
it
D
This
To pay to see that movie seems foolish ________ you can see it on television for free.
#31010
A
before
B
though
C
when
D
once