one of our rules is that every student shall wear

问题描述:

one of our rules is that every student shall wear
school uniform while at school 为什么用 while

while 指在.的时候那为什么不用whenat又是为什么when一般指时间点,而while一般指时间段,at school是指在学校期间,属于时间段,所以用while