This exam is very difficult. Many students are concerned ______ the results. [ ]

A. about

B. with

C. to

D. of

我国现存规模最大、保存最完整的清真寺是( )。

A．广州怀圣寺

B．泉州清净寺

C．北京牛街礼拜寺

D．西安化觉寺