◆他能通過考試。

誤：He can be able to pass the exam.

正：He can pass the exam. / He is able to pass the exam.

析：be able to 不能與 can 用在同一個(gè)謂語中。

◆這工作可按時(shí)完成。

誤：The work is able to be finished in time.

正：The work is capable of being finished in time.

正：The work can be finished in time.

析：按規(guī)范語法：be able to之后一般不接動(dòng)詞的被動(dòng)式，盡管在 現(xiàn)代英語中已有人打破此規(guī)則，但初學(xué)者仍以不用為宜。

◆他在公共汽車后面追，并追上了。

誤：He ran after the bus, and could catch it.

正：He ran after the bus, and was able to catch it.

析：表示過去特定情況下的能力，可用 was (were) able to 而不 能用 could，不過這種差異在否定句中便不存在了。如：He ran after the bus but wasn’t able to [couldn’t] catch it.