※ 引述《forkome (初心者)》之銘言：
: 請教大家一下
: 今天上英文課時，教一種句型
: We were walking on the beach when it began to rain.
這裡的when = at or during which time
He was still smiling when the door opened and his wife came in.
We were about to star when it began to rain.