改错 He could be able to skate when he was seven years old

问题描述:

改错 He could be able to skate when he was seven years old

应该改为如下正确形式:
He was able to skate when he was seven years old
be able to do 能够做某事。。。

He was able to skate when he was seven years old
could be able to 意义重复