1. 当有利时：as occasion requires 在必要时 | as occasion serves 当有利时 | as of old 依旧

2. 一有机会就：56、as much as to say ......等于说 | 57、as occasion serves 一有机会就 | 59、as often happens 如同经常发生那样

3. 一有机会,一有适当时机,方便的时候：as follows 如下 | As occasion serves 一有机会,一有适当时机,方便的时候 | As the matter stands 按照现状

4. 一有适当的时机：as occasion requires 遇必要时 | as occasion serves 一有适当的时机 | as occasion offers 有机会时, 机会到来时