Mrs. White found her husband surrounded by letters and papers and _____ very worried. [ ]

A. look

B. looks

C. looking

D. to look

（l）下列说法正确的是

A．密闭房间内，温度升高，空气的相对湿度变大

B．密闭房间内，温度越高，悬浮在空气中的PM2.5运动越剧烈

C．可看作理想气体的质量相等的氢气和氧气，温度相同时氧气的内能小

D．系统的饱和汽压不受温度的影响