i can speak english 情态动词是什么作用?
问题描述：
i can speak english 情态动词是什么作用?
答
表达"能力".（体力、知识、技能、容量）
Can you lift this heavy box?（体力）
Mary can speak three languages.（知识）
Can you skate?（技能）
This hall can hold 500 people at least.（容量）
注：此时可用be able to代替.
No one is able to do it.(= No one can do it.)
区别：can（一般现在时）和could (一般过去式)；而be able to通过be的变化则有更多的时态,它也可以用于不定式或与其他助动词或情态动词连用,can 或 could则不可.
I’m glad to be able to attend your wedding party.
She might be able to play the role.
I haven't been able to find any jobs.