Do tell me the way you think of ______ the problem as soon as possible.

A．to solve

B．solving

C．solve

D．being solved

影响北京地区空气质量的气体污染物主要是[ ]

A．CO₂、O₂、N₂

B．SO₂、NO₂、CO

C．CH₄、CO₂、SO₂

D．HCl、CO₂、N₂