A:表达载体中的胰岛素基因可通过人肝细胞mRNA反转录获得
B:表达载体的复制和胰岛素基因的表达均启动于复制原(起)点
C:借助抗生素抗性基因可以将含胰岛素基因的受体细胞筛选出来
D:表达载体中的启动子和终止密码子均在胰岛素基因的转录中起作用
我国水资源的空间分布特点是____。
The world is divided into two parts. One half of the world is rich and 1is poor. In the poor part, a lot of people have2got enough to eat. When they are ill, none of the3can receive them because they have no money. In the rich 4, people eat very well, 5 a dog or a cat in North America eats 6than a child in poorer countries. The poor countries have some difficult problems. Sometimes the land is too poor to grow7on. People there have 8rich land nor enough water. The land9be made better, but a lot of things must be done. The people must be taught and water must10. But rich countries have problems, too. There are not always good places to 11. Sometimes the air is not clean and the rivers are too 12to swim in or to drink. The roads and streets are full of people and cars. Cars and buses have to move 13. Noise is too much. Some people have no houses to live in. Something must be done about these problems. The air and the rivers must be cleaned and be 14clean. More houses have to be built. 15these things cannot be done easily.
如图,点E在BC上,AB//DE,∠B=80°,∠C=60°,则∠EDC的度数为( )
在直角三角形中,如果各边都扩大1倍,则其锐角的三角函数值( )