一个圆形水池的周长是62.8米，这个水池的占地面积为多少平方米？
62.8÷3.14÷2=10（米），3.14×102=314（平方米）
肺痿的临床主症是
A．咳吐浊唾涎沫
B．痰多清稀色白
C．痰黄黏稠
D．痰黏结块
E．痰呈泡沫
Which step should normally be taken FIRST by those who have boarded a liferaft in an emergency?（）
A.Ration food and water supplies
B.Take anti-seasickness pills，if available
C.Determine position and closest point of land
D.Check pyrotechnic supplies
