His contentions cannot be laughed out of court.

对他的争辩不能一置之。

A childish idea like that can be amusedly tolerated.

像那样幼稚的想法可以一置之。

He had a bad fall while ice-skating but he laughed it off.

他滑冰时重重地摔了一跤, 但他一置之。

He poohpoohed the idea.

他对那个意见一置之。

On abuse, on reproach, on calumny, it is easy to smile; but painful indeed, is the panegyric of those we contemn.

面对谩骂、非难，中伤而一置之，那是容易的；可是，老实说，要藐视这些颂词却是需要费点儿力气的。