He is really a tough guy; he takes no prisoner.
他很严格, 手下绝不留情.

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这是我听老美形容他们教授的, 就是说他们教授很严格,而且绝不留活口。所谓takes no prisoner指的是战争时不收战俘, 抓到全部杀死的意思, 也就是说够狠. 老美常用 tough 来形容一件事情的困难或是一个人的强硬态度, 例如, "Today is a tough day for me." 就是说今天过得很不容易啦. 要是说 "The professor is tough." 则是说这个教授教课很严格, 很不好混的意思. 要是别人遇到这种 tough 的教授, 你就可以鼓励他, "Tough it out!" 就是说把它撑过去.
同样地, 这句话你也可以说成 "The professor goes for kill." 就是说这个教授支持杀戮. 下手绝不留情.

he  is really a tough guy ,he  takes no prisoner.

the beauty scared me! she seemed a tough guy and took no prisoner.

he‘s really a tough guy,he takes no prisoner.
today a tough day for me.

Today is tough day for me.

Today is tough day for me.

He is really a tough guy,he takes no prisoner.

Mr. Sharam is really a tough guy, he takes no prisoner.

A: How about your professor !
Bon't metion him , he is really a tough guy ;he takes no prisoner .

he is really a tough guy; he takes no prisoner.
take no prisoner
today is a tough day for me.
the professor is tough.
tough it out!