如图所示，三层供水管路，各管段的s值皆为10⁶s²/m⁵。层高均为5m。设点a的压力水头为20m，Q₁，Q₂，Q₃大小分别为()

A．4.47L/s，2.41L/s，0.63L/s

B．44.7L/s，24.1L/s，6.3L/s

C．447L/s，241L/s，63L/s

D．4.47m3/s，2.41m3/s，0.63m³/s

（A man and a woman are talking at the Shanghai Hongqiao Airport.）

M：The airplanes are late, aren’t they?

W：  1  I never expect planes to be on time.

M：Are you working here or just a visitor?

W：A visitor.

M：How long have you been here?

W：  2 

M：What places of interest have you been to?

W：Quite a lot, like the Great Wall in Beijing, West Lake in Hangzhou. They’re really wonderful.

M：3 

W：You know, China is a country with a long history and it’s quite beautiful.

M：  4 

W：Yes, of course. It’s delicious.

M：Oh, here’s my airplane at last. I must go now. Bye.

W：Bye!   5 

M：Me, too. Take care.