The following statements , _____, illustrate the functions of calcium.
A. nerve cells need calcium for nerve impulse conduction
B. muscle needs calcium to contract
C. blood needs calcium to clot
D. bone needs calcium to make itself hard
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If the hemostasis maintained between the action of osteoblasts and osteoclasts is broken, what might happen?
A. The surplus of calcium in the bone may form spurs.
B. A loss of too much calcium weakens the bones.
C. A loss of too much calcium might cause the bone to break easily
D. if bone loses two much tissue, it may become very flexible.
What are the influential factors that affect normal bone growth?
A. hormones
B. minerals
C. vitamins
D. enzymes
社会存在是指社会的物质生活条件,它有多方面的内容,其中对人类社会存在和发展起决定作用的是( )
A. 社会形态
B. 地理环境
C. 人口因素
D. 物质资料的生产及其生产方式
社会意识相对独立性最突出的表现是( )
A. 社会意识内部各种形式之间的相互作用和影响
B. 社会意识与社会存在发展的不完全同步性
C. 社会意识各种形式各自具有历史继承性
D. 社会意识对社会存在具有能动的反作用
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