成人英语三级考试

【单选题】He had already walked three or four miles ______ he saw a cart, half-full of hay, by the side of the road.


A．while
B．when
C．the moment
D．unless

网考网参考答案：B
网考网解析：
[考点] when的用法 [解析] when“这时(突然)”。常见的搭配有：be doing…when…；be about to do…when…；had done…when…。例如：I was walking in the street when someone called me from behind.我走在街上，突然有人从后边喊我。I was about to go out when he came in.我正要出门，突然他进来了。 查看试题解析出处>>