Some children aren't able to speak before they are two years

来源：学生作业帮编辑：作业帮分类：英语作业时间：2024/08/23 03:37:37

Some children aren't able to speak before they are two years old.
上面的为什么不能用can't 而要用 aren't able to .不是说can表示自身能力的吗?

can表示的是一种主观能动性,自己能控制的,而be able to 是由客观条件所决定的.
再问：只要是人身上的技能都用can吗？例如，我学了很久才学会唱歌。
再答：应该是这样的，I can do something. 但有时也可用其它说法。比如说一件事你可以通过自己的努力学会或者是完成就可以用can，这就是主观能动性。
再问：但书上说努力而成的能力要用 be able to 啊。。算了。不纠结了。。

请翻译：Some children aren't able to speak before they are two. 选词填空：1、Some children______(couldn’t/aren’t able to)speak bef There aren't any children in the room ,are they? .They aren't very kind to each other, are they? It's our duty to help b___ people because they aren't able t It's our duty to help (b ) people because they aren't able t Forests are very important to us ,aren't they? they have (able)to speak english well they are going to the park,______(aren't they? won't they?) they are going to the park,______(aren't they?won't they?) Some people are h____.They always do their best.They aren't There are some shoes under the chair __?A.are they B.aren't