问题

_______you return those books to the library immediately, you will have to pay a fine.[ ]

A: Until
B: Unless
C: If
D: Provided

正确答案是：

同类题型

_____ giving us a hand, he stood there laughing[ ]

Don’t you think ___ important to care for our earth

I’m sorry. I’ve forgotten my credit card.And I don’t have enough money for the meal.— Don’t worry. ________.

There is _______milk in this glass than in that one.

Hardly could he ________ this amount of work in such a short time.