16个月男孩，因发热、咳嗽5天入院，诊断为肺炎，入院后持续高热，第3天病情突然加重，

一辆汽车3小时行了246千米，平均每小时行多少千米？

比例代表制

WHO代表是什么？

A VLCC (100，000 DWT+) with a 30，000 Shaft Horsepower Steam Turbine is slow to respond to engine movements and has less stopping power than normal ships because it has a（）.

A.bigger propeller

B.smaller power to weight ratio

C.smaller propeller

D.larger power to weight ratio

大气专题主要说明哪些问题？