儿童的骨柔韧有弹性、不易骨折,但易变形,原因是骨成分的含量 （ ）
A．有机物约为2/3，无机物约为1/3
B．有机物约为1/3，无机物约为2/3
C．有机物多于1／3,无机物少于2／3
D．有机物少于1/3，无机物多于2/3
答案：C
题目分析：骨的成分包括有机物和无机物，有机物越多，骨的柔韧性越强，无机物越多，骨的硬度越大；在不同时期，骨的成分不同，如下表：
所以在儿童青少年的骨中，有机物多于1/3，骨的弹性大，容易变形，所以青少年要注意坐、立、行的姿势。故选：C
Stress(压力) is everywhere in our everyday life. Not only men have it, but also women and young people. The most important reasons of stress are: diseases, exams, making money, getting married, moving houses, changing jobs, ending friendships and so on. How do you know whether you have stress? Give your answers to the following questions?全
Doing relaxing exercises, talking with friends and listening to light music are all usual ways of relieving(减轻) stress. However, doctors now say that there are easier ways --- people should laugh and smile more often. When you laugh and smile, your body relaxes. They also say that people, especially men, should cry more often, because crying is the natural way of relieving stress. 小题1:If you have over ________ problems listed in the table, you are the person with stress.
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