如何用英语表达有能力和无能力

I can manage it myself.

我自己可以做到.



I'm capable of keeping a secret when necessary.

必要时我是可以保守秘密的.

My brother is able to speak three foreign languages.

我的兄弟可以说3门外语.

We know how to contact with him.

我们知道如何与他取得联系.

She is unable to settle the debt with such a short period.

她不能在如此短的时间内偿清债务.

Mary doesn't know how to mend her telephone.

玛丽不知道如何修理她的电话.

Trees are incapable of growing without sunshine.

树在无阳光的地方不能生长.

There's nothing I can do about it.

我无能为力.