The porter, however, could not understand me.

看门人却听不懂我的话。

youdao

I could not understand why she felt compelled to behave so rudely to a friend.

我不能理解为什么她非要如此粗鲁地对待一位朋友。

《柯林斯英汉双解大词典》

He could not understand how people paid for food and valuable things with paper!

他无法理解人们是如何用纸来购买食物和贵重物品的！

youdao

Brown could not understand the fear that kept the slaves from fighting for their freedom.

VOA: special.2009.07.02

We're also going to recognize, however, that insurance got a slow start because-- I believe it is because-- people could not understand the concept of probability.

不管怎么说,我们得承认,保险起步缓慢,因为...,我相信是因为...,人们无法理解概率的概念

耶鲁公开课 - 金融市场课程节选

She could not understand why he killed the birds he seemed to like so much.

VOA: special.2010.04.03

He said he could not understand why engineers had installed humps in his street.

BBC: Hearses halted by speed humps

The mother-of-two's husband William, 77, said he could not understand why anyone would want to hurt her.

BBC: Sybil Sibthorpe

However, Mr Worboys said she suddenly began swearing at him, adding that he could not understand why.

BBC: Sex charge cabbie admits to lying