问题 问答题 简答题

心室肌细胞动作电位可分为哪几个期?各期形成的主要原因是什么?

答案

参考答案:

心室肌细胞动作电位分为0、1、2、3、4期。0期为Na内流;1期为K外流;2期为K外流与Ca内流;3期K外流;4期膜电位稳定为Na-K泵活动。

阅读理解

  People use money to buy food, furniture, books, bicycles and hundreds of other things they need or want. Most of the money today is made of metal or paper. But people used to use all kinds of things as money. One of the first kinds of money was shells. Shells were not the only things used as money. In China, cloth and knives were used. In the Philippine Islands, rice was used as money for a long time. Elephant tusks, monkey tails, and salt were used as money in parts of Africa.

Some animals were used as money too. The first metal coins were made in China. They were round and had a square hole in the center. People strung them together and carried them from place to place. The first coins in England were made of tin (锡). Sweden and Russia used copper (铜) to make their money. Later countries began to make coins of gold and silver.

Later the Chinese thought of a way to improve money. They began to use paper money. Money has had an interesting history from the days of shell money until today.

小题1:People used different kinds of things as          .

A.gold

B.metal

C.money

D.silver小题2:Tin was first made as money in         .

A.China

B.Philippine Islands

C.England

D.Russia小题3: The word "strung" in the passage probably means         ."

A.came

B.tied

C.put

D.made小题4: The best topic of the article is”         .”

A.How Many Kinds of Money Are There in the World

B.The History of Money

C.Money in Different Countries

D.The Use of Money

单项选择题