分类：教育/科学-外语学习
问题：英语问题theycried()itbegantorainAwhe 
they cri( )it began to rainA whenB while为什么选B不选A
回答：A.when意为"在……时;当……时",可表示"点时间"或"段时间",从句谓语可以是终止性动词,也可以是延续性动词。例如: 
When I got home, he was having supper. 
B.while只可表示"段时间",从句谓语只限于延续性动词。例如: 
While I was sleeping, my father came in. 
注:从句谓语是持续性动词时,when、while和as可以互换?主?从句谓语都是终止性动词时,when与as可互换?从句谓语表示状态时,通常用while.  而题目中有began为过去时，是延续性动词，所以选b