翻译几个单词和短语，不复杂，不反对用翻译软件

cruel, heartless

There's an old saying:?Even the most curel animal will not eat their own children.

When..., have we paid attention

human

human being, man, person

不反对用翻译软件？哈哈你真搞笑。
无情的：hard-hearted, heartless, pitiless
俗话说，虎毒不食子Folksay:Vicious as a tigress can be, she never eats her own cubs.
当。。。的时候：when, while, as
我们可曾注意到：Are we ever aware of......?
人类：human being
人：people, person, man

unmerciful 无情的

as the saying is : Tiger poison not food son
when the time...
we have to note that
human being
1. man
2. person
3. people

除了第二条：Dog doesn't eat dogs!
其他均同意楼上的回答