| 电气化铁路的输电线常用图所示的方式悬挂在钢缆上．钢缆的A端固定在电杆上，B端连接在滑轮组上．滑轮组由a、b、c三个滑轮构成，配重P由多个混凝土圆盘悬挂在一起组成，配重的总重为G，若不计摩擦和滑轮的重量，则以下说法中正确的是（ ） A．a为动滑轮，B端钢缆受到滑轮组的拉力大小约为3G B．a为动滑轮，B端钢缆受到滑轮组的拉力大小约为 C．a、c为动滑轮，B端钢缆受到滑轮组的拉力大小约为3G D．a、c为动滑轮，B端钢缆受到滑轮组的拉力大小约为  |
答案：A
Now more and more people may experience excessive (more than normal) hair loss(掉发). Hair loss of this type can affect men ,women and Children. But what causes excessive hair loss?
A number of things can cause excessive hair loss．For example，about 3 or 4 months after an illness，you may suddenly lose a large amount of hair ,This hair loss is related(与……有关)to the stress of the illness and it won’t last long．
For example，many women notice hair loss about 3 months after they’ve had a baby .This loss is also related to hormones (激素). During they have babies，high levels of certain hormones cause hair loss. When the hormone return to normal levels．The normal cycle of growth and loss starts again.
Another way of hair loss is the improper care of your hair .If you wear pigtails(辫子)or use tight (紧的)hair rollers, the pull(拉)on your hair can cause a type of hair loss.
Some medicine can cause hair loss．This type of hair loss improves when you stop taking the medicine．Medicine that can cause hair loss includes blood thinners，medicine used to treat cancer ,Vitamin A(if too much is taken)，birth control pills and so on．
But how to stop hair loss ? Perhaps your doctor can help you．He will probably ask you some questions about your diet，any medicine you’re taking，whether you’ve had a recent illness and how you take care of your hair．
Medicine may also help slow or prevent(阻止)the development of hair loss Some medicine is helpful．but you had better ask for doctors’ advice .
任务：请阅读上面短文，根据短文内容完成下面表格中的有关信息。
| What causes hair loss? | How to stop hair loss? |
| Hair loss is related to小题1: | Doctors can help you |
| The 小题2: may cause hair 1oss, such as wearing pigtails ,using tight hair rollers and so on. | 小题3: may help prevent hair loss if doctors permit. |
| 小题4: can cause hair loss. |
G
G