Question

be able to 书上说只用be able to的情况有一种是位于情态动词后之前还说be able to是情态动词那

Answer 1

You'll be able to come,won't you?

你能来的,对吗?

看以上这个句子,这就是be able to位于情态动词后的用法.

而且,be able to本身并不是情态动词.他只是相当于情态动词.

情态动词只有四种：

1.只做情态动词：must,can(could),may(might),ought to

2.可做情态动词又可做实义动词：need,dare

3.可做情态动词又可做助动词：shall(should),will(would)

4.具有情态动词特征：have(had) to,used to