be able to可和有生命的主語甚至與無生命的主語連用：I have not been able to write for several days—G. Vidal, 1955; a yarn about not being able to keep a job—K. Amis, 1978;By his proceeding to the beach ... the next phase of the attack was able to proceed—New Yorker, 1986賦予無生命主語以能力,并不總是可取的,如果所接的動詞不定式是被動的,那句子就很勉強(qiáng)：No evidence that an air rifle was able to be fired— Times (heading of Law Report), 1988.總體上,最好用情態(tài)動詞can/could 加被動式,或者把句子寫成主動的形式【題】That mistake is ____ corrected.