问题

________ you understand this rule, you’ll have no further difficulty

A:Once
B:Unless
C:As
D:Until

正确答案是：

同类题型

I _____to go for a walk——-But I_____ going shopping

下列各句中，没有语病的一项是（）

Liu Ying is ______than Wang Mei.

Thank you very much __________me __________your birthday party.

The motto of the modern Olympics is “_______. ”