想要祛毛，我们必须先了解毛发的生理和生长周期。
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毛发的生理：
* 毛发主要由两大部分组成：
    -毛干，是可见部分，对毛发的生长几乎没有影响。
    -毛囊，是在皮下组织（皮肤里面），能决定毛囊的生长。
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毛发的生长周期：
1）生长期
-通常情况下，人体大约有85%的毛发处于生长期，毛发的生长期可能长达2-6年。毛发每年约生长10cm（不同部位的毛发，生长的长度也不同），但长度一般不会超过1m。
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2）过渡期
-毛发在生长期完结后，就进入了过渡期，过渡期一般仅维持1-2周。在过渡期中毛囊回收缩至正常的1/6.
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3）休眠期
​-休眠期的毛发不会生长，但依然与毛囊相连，休眠期一般会持续5-6周。人体中大约有10-15%的毛发处于休眠期。
​​To remove hair, we must first understand the physiology and growth cycle of hair.
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Physiology of hair:
* Hair consists mainly of two parts:
   -Hair shaft, which is the visible part, has little effect on hair growth.
   -The hair follicle is the subcutaneous tissue (inside the skin) that determines the growth of the hair follicle.
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Hair growth cycle:
1) Growing period
- Typically, about 85% of the body's hair is in the growth phase, and the hair growth period may be as long as 2-6 years. Hair grows about 10 cm per year (the length of hair grows differently in different parts), but the length generally does not exceed 1 m.
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2) Transition period
-After the growth period of hair is completed, it enters a transition period, which generally lasts only 1-2 weeks. During the transition period, the hair follicle recontracts to 1/6 of normal.
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3) Dormant period
-Dormant hair does not grow, but is still attached to the hair follicle, which usually lasts for 5-6 weeks. About 10-15% of the hair in the human body is dormant.
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