人体的运动由运动系统来完成，运动系统的功能是[ ]
A．促进血液循环
B．运动、支持和保护
C．促使心肌发达
D．提高肺的通气能力
答案：B
选择正确的词语填空。
1. Mittens and __________ (mitt, mitts) are the same.
2. There are four __________ (season, seasons) in a year.
3. Many __________ (people, peoples) say he was Jesus.
4. We are __________ (arrive, going to arrive) tomorrow.
5. He is __________ (taking off, put on) his hat.
水在垂直管内由上向下流动，相距l的两个断面间，测压管水头差为h。如图所示。则两个断面间沿程水头损失为（）。
A.h
B.l-h
C.l+h
D.h-l
