By the time the new pupil ___ enough courage to raise his hand, the bell__ for the end of the lesson

A．had gathered…was already ringing

B．was gathering…had already rung

C．gathered… had already rung

D．would gather… have rung

旅游企业中的人文精神要坚持以人为本，要求做到（）。

A.以贵宾为本

B.以员工为本

C.以经营者为本

D.以公众为本

E.以顾客为本