英语中有多种表示"一...就..."的句型,例如,常用连词as soon as,no sooner .than.,hardly .when ...;同时,也有介词at 和on来表示.
介词at和on在使用时,at 常后接名词,表示"一看到..."或者"一听到...",而on往往后接动词的-ing形式或者表示动作意义的名词.例如:
Everyone in the hall got excited at the news that Hengda Football Team won first place.(这里at+news表示一听到)
She was frightened at the sight.(此处at+sight表示一看到)
He began to work on his return/arrival(此句话中return或者arrival 均表达动作意义,所以其前不能用at)