问题

This kind of game is exciting.—Yes, but it’s dangerous. One can’t do it ________ he or she has got some training.

A:if
B:after
C:when
D:Unless;

正确答案是：

同类题型

I’m trying to find yesterday’s newspaper. Have youseen it—I’m afraid that I ________ it away. I thought youhad finished reading it.

I wonder ________ you’ll water this kind of flower—Once a week

George returned after the war, only _______ that his wife had left him. [ ]

Gone are the days ________ we spent together in the mountainous village.

They have made a very pretty job of it. I think they deserve to be _____. [ ]