詞語 increase 一問

當increase 和 decrease 這兩個詞語被用作 transitive verbs 的時候, 就能夠使用在被動句式中。
例子:
Active: His boss finally increases(decreases) his salary.
Passive: His salary is finally increased(decreased) by his boss

當increase 和 decrease 這兩個詞語被用作 intransitive verbs 的時候, 就不能夠使用在被動句式中。
例子:
Active: The population of Hong Kong has increased steadily.
Passive: 因為這句的 increased 是 intransitive verb，所以不能轉 passive。

你中學英文老師用的是 intransitive verb 例子，例如： his weight has increased/decreased，所以這兩個詞語不能使用在被動句式中。

但是，如果用 transitive verb 的例子，例如：Peter increases/decreases the weight of his model car by adding metal wheels to it，就可以轉 passive:
The weight of his model car is increased/decreased by Peter by adding metal wheels to it.


2009-06-19 07:49:36 補充：
His salary has been increased (v.t.) 和 His salary has increased (v.i.) 意味上 (implication) 有分別。因為第一句是省畧了加他人工的人(他的老板)，即意味着他做工做得好，他老板特意加他人工。第二句只是說他加了人工，可能是每年慣性調薪，沒有意味有人特意加他人工。

It can be used in passive in different circumstances.
The rent has been increased since January.
The school fee or management fee has been decreased.
You have gained weight but not increased weight.