问题

You must keep on working in the evening _____ you are sure you can finish the task in time.[ ]

A: as
B: if
C: when
D: unless

正确答案是：

同类题型

Bob is____ honest boy, and he won’t tell lies

下列四个选项中，划横线虚词的意义和用法全都一样的一项是（）

___________– It is fiveshillings.

What did Yang Ying say-She said they______ a school trip the nextweekend.

If you _____ the bottle and cigarettes, you we’ll bemuch healthier.