can not=can't=can not 不能; 不可能

Since the birds interbreed they cannot be classed as different species.  

由于这些鸟进行杂交繁殖，不能把它们归为不同的物种。

The worms cannot be seen by the naked eye.  

这些虫子用肉眼看不见。

The matter can not be discussed except at a personal interview.  

这件事只能在面谈时讨论.

It can not be measured in terms of money.  

这是不能用金钱衡量的.

I'm a blood donor; I can't risk any contagion.  

我是献血者，我不能冒任何接触传染的危险。

"I can't give you an answer now," he hedged.  

“我现在不能回答你，”他闪避道。

I can't think of a worse way to spend my time.  

我想不出更糟的消磨时间的办法。