1. be able to do sth. 有能力做某事；能。

     Will you be able to come? 你能来吗？

     You are better able to do it than I am. 你比我更有能力担任此事。

2. be afraid of  

    1)  害怕：畏惧

      There's nothing to be afraid of? 没什么好害怕的。

      Are you afraid of snakes? 你怕蛇吗？

    2）恐怕

    I was afraid of hurting his feeling.

   = I was afraid that I might hurt  his feeling.  我恐怕伤了他的感情。

另：be  afraid  to 担心，不敢