Question

___ the beginning of the meeting, the president made a speech ___ how to reduce pollution.

A．a(chǎn)t; in

B．a(chǎn)t; on

C．in; on

D．on; on

Answer 1

B解析:
固定搭配at the beginning of在…的起初。on表示關(guān)于某種問題。