① allow sb. to do sth.允许某人做某事
Please allow me to carry your bag.
请让我替你拿包。

② allow doing sth.  允许做某事
They allowed smoking in this room only.
他们只允许在这间屋子里抽烟。

③ allow常与 out, in, up等副词搭配使用，即 allow sb. in/out/up等。

She won't allow the children in until they've wiped their shoes.
直到孩子们把鞋擦干净，她才让他们进来。

The patient was allowed up after ten days.
十天后病人才被允许起床(下地)。