can可作及物动词、名词和情态动词,意为可以、炒…的鱿鱼、金属罐、塑料容器、能、会,只有一般现在和一般过去两种时态。
be able to作为动词,意为能够;(因具有品质或技能)能做到…的;(因有足够的自由、权力、时间、财力等而)可以…的。可以有各种时态。
1、I doubt they'll be able to help but it's worth a try.
我不敢肯定他们能够帮得上忙,但不妨试一试。
2、He should be able to lead a perfectly normal life.
他应该能够过上完全正常的生活。
3、I have some information you may be able to use.
我有些可能对你有用的信息。
1、The operation could prolong his life by two or three years.
这次手术可使他多活两三年。
2、I'll see what I can do to help.
我考虑考虑,看我能帮上什么忙。
3、I don't know how you can say things like that.
真想不到你怎么会说出这种话来。