I can't drink.
I don't drink.
一个是不会,一个是会喝因某些外在因素不喝.
I'm unable to drink.和 I can't drink.都是我不能喝酒的意思
这点可以肯定,
因为can [kæn,kən]
aux.v.
表示 能,能够
If you won't keep quiet you can get out!
如果你不保持安静,那就只好请你出去了!
参考词汇
can ,able ,managed to
was(were) able to 和 could 在表示“能力”时可以换用,当 was (were) able to 表示经过努力或克服了困难之后做成了某事时便不能与 could 换用,却能与 managed to 或“succeeded in+动名词”换用
Then he spoke slowly,but I could not understand him.
至于不喝酒,根据场景不同会有很多种不同的说法,一般不会这样直接的说,你可以说I prefer orange juice.