He doesn't say those silly things that unthinking people say.

他不说那些考虑不周的人才会说的傻话。

His unthinking words had hurt her deeply.

他轻率的言词深深地伤害了她。

This book will not profit an unthinking man.

这本书对不善于思考的人毫无益处。

To this the unthinking will give an off-hand answer .

给我一个直截了当的答复。

Unthinking, he threw his lighted match into the waste paper basket.

他想也没想就把燃着的火柴扔进了废纸篓里了。