It is not within my power to help you.
我是愛莫能助啊。
It is not clear what they want us to do.
我們不肯定他們要我們做什么。
Her work is not up to standard.
她的工作不合格。
It is not often that you get such an opportunity.
你得到這樣的機會，可不是常有的事。
The problem is not primarily a financial one.
這個問題基本上不是財政問題。