You must show no mercy here.

你不能在这里表现出怜悯。

He showed no mercy to anyone.

他对任何人都没有怜悯。

So this means that in a war, one army showed no mercy, no compassion, no kindness for someone else.

所以这意味着在一场战争中， 一支军队对其他人没有怜悯、同情和仁慈。

The group showed no mercy. Again and again, they kept asking, " Who read you that story? "

这群人毫不留情。一次又一次，他们不停地问：“谁给你读了那个故事？”