be able to do sth 更多用于什么时态?

be able to do sth 更多用于什么时态? be able to do sth 等于什么 be able to do sth being able to 用于什么时态? 用be able to do sth造句 英语 翻译 be able to do sth be able to do sth 意思 用法! be able to 和 can 分别用于那种时态? be able to do sth be able to do sth 的同义词是什么? may not able to do sth 还是 may not be able to do sth? I imagine sb.to be able to do sth. be not able to do sth be unable to do sth区别