あんなことを彼女に言うなんて非常識も甚だしい。

It's quite absurd of you to tell her that sort of thing.

彼はやたらに故事来歴に詳しいけれど、それが人生の役に立っているのかはなはだ疑問だね。

He has a great storehouse of knowledge about historical details but I seriously doubt that's of any use in life.