It is not within my power to help you.
我是爱莫能助啊。
It is not clear what they want us to do.
我们不肯定他们要我们做什么。
Her work is not up to standard.
她的工作不合格。
It is not often that you get such an opportunity.
你得到这样的机会，可不是常有的事。
The problem is not primarily a financial one.
这个问题基本上不是财政问题。