问题
The secret of happiness is to treasure the things you have now. But someone won’t know it _______ they lost what they own.
A:if
B:while
C:since
D:until;
B:while
C:since
D:until;
正确答案是：
同类题型
Which of the following doesn’t belong tothe Four Great inventions of Ancient China
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You ought to have called her yesterday . — Yes , I know I ____ .
118. The United States is trying to _______the serious problems resulting from the energy crisis.