Question

A new ________ bus service to Tianjin Airport started to operate two months ago.

A．normal

B．usual

C．regular

D．common

Answer 1

C

normal正常的( normal temperature, return to normal); usual通常的（usual time, usual restaurant); regular定时/期的，有规律的（regular breathing; a regular bus service ）; common一般的，常见的（common sense, common names）。