观察胸腔闭式引流的最简单方法是（）。

A.胸腔内有积气

B.长玻璃管中的水柱上下波动

C.引流液性质和量

D.引流的速度，有无出血

E.胸腔内有积液

After staying in hospital for long, the patient was advised to go to the seaside to   _____   his health.

A．take up

B．pick up

C．carry up

D．make up