when
The Queen's last visit was in May,when she opened the new hospital.
女王上次来访是在五月份,她那时主持了这座医院的落成典礼.
How can they learn anything when they spend all their spare time watching television?
他们把所有的空闲时间都用来看电视了,还能学什麽东西呢?
It was the sort of morning when everything goes wrong.
那天上午就是那样,事事不顺心.
It was raining when we arrived.
我们到的时候正在下雨.
He was fond of drawing when he was a child.
他还是个孩子时就喜欢画画
while
I lived in a hostel while I was a student.
我求学期间住在青年招待所里.
She worked in a bank for a while before studying law.
她学法律之前在银行工作过一段时间.
While Mary was writing a letter,the children were playing outside.
玛丽写信时,孩子们在外面玩耍.
I haven't seen him for a long while.
我已经很久没见到他了.
Turn off the switch while anything goes wrong with the machine.
如果机器出故障,就把开关关掉.