inquire after

1. 問候
   She inquired after my mother's health.

   她問候我母親的健康。

inquire for

1. 求見
   A man has been inquiring for you at the office.

   有人在辦公室想見你。

inquire into

1. 調查
   We must inquire into the matter.

   我們必須調查此事。