有关原发性（姿态性）脊柱侧凸，下列哪项是错误的（） A.占脊柱侧凸畸形的80% B.

阅读理解。

     All living things on the earth need other living things to live with.  1  Sometimes one living thing kills

another. Each kind of life eats another kind of life in order to live, and together they form a food chain

(食物链).  2  while others are not. But all food chains begin with the sun, and all food chains become

broken if one of the links disappears.

     All life needs sunlight to live on.  3  They make food from sunlight, water, air and so on. Animals can

only use the sun's energy after it has been changed into food by plants. Some animals feed directly on plants.

Others eat smaller animals. Meat-eating animals are only eating plants indirectly. 

      4  We are members of many food chains. We eat wheat, rice, vegetables, fruit and so on. We also eat

meat and drink milk. But people often break up the food chains. They kill wild animals. They also make rivers,

lakes and seas dirty.  5  the fish in them cannot be killed. If people eat the fish, they will get strange

diseases. Each form of life is linked to all the others. Breaking the links puts all life in danger.

A. When these rivers, lakes and seas are polluted,

B.  But only plants can use sunlight directly.

C.  Some food chains are simple,

D. What about human beings?

E.  Nothing lives alone.

垂体性侏儒症患者进行生长激素释放激素兴奋实验时，由下丘脑原因引起者，兴奋后GH的峰值为（）。

A.>5μg／L

B.>10μg／L

C.5～10μg／L

D.<10μg／L

E.<5μg／L

将“568400000”省略亿后面的尾数取近似值约是______亿．

如果叶轮在临界浸没水深以下，不仅负压区被水膜阻隔，而且水跃情况大为削弱，甚至不能形成水跃，并不能起搅拌作用。

韭菜的体细胞中含有32条染色体，这32条染色体有8种形态结构，韭菜体细胞中有几个染色体组（）

A.二

B.四

C.六

D.八