What impresses me most is ______ he appears in front of others, he wears a sincere and charming smile．

A．which          B．that        C．where      D that whenever

液化石油气储配站，站址应选在( )，与服务站之间的平均距离不宜超过( )。

A．城市中心区；20km

B．城市郊区；25km

C．城市边缘；10km

D．靠近用气大户；5km