英语单选
Mostofusknowweshouldcutdownonfat,butknowingsuchthingsisn'tmuchhelpwhenit_____shoppingandeating.
A.referstoB.speaksofC.focusonD.comesto
First,句中","后为什么用knowing,而不用know.Second,正确答案是什么.望简洁易懂的答案,并把句子翻译一下,望翻译得流畅准确一些.