问题

Youshouldnotgorafting__________youknowhowtoswim,andyoushouldalwayswearalifejacket[ ]

A:though
B:unless
C:until
D:if

正确答案是：

同类题型

Irene, do you really want to go out—It may rain. ___________, I will go out; I don’t mind the rain.

helike singing —Yes, he .

The little boy looked at the cake with eyes.[ ]

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Lucy is a girl of great musical _________,and I’m sure she will become a well-known musician sooner or later.