心脏的自律性来源于 A．心脏特殊传导系统 B．心血管中枢 C．心室肌细胞 D．交感神

镁在二氧化碳中燃烧的化学方程式为 2Mg+CO2====C+2MgO。该反应属于

A．化合反应

B．分解反应

C．置换反应

D．复分解反应

肾上腺素的临床应用包括：（）

A.支气管哮喘

B.心律失常

C.过敏性休克

D.重症肌无力

E.心脏骤停

In Canada you can find dogs, cats, horses, etc. in almost every family. These are their pets. People love these pets and have them as their good friends. Before they keep them in their houses, they take them to animal hospitals to give them injections(注射)so that they won't carry disease. They have special animal food stores, though they can get animal food in almost every kind of store. Some people spend around two hundred Canadian dollars a month on animal food. When you visit people's houses, they would be very glad to show you their pets and they are very proud of them. You will also find that almost every family has a feeding place for birds in their garden. All kinds of birds are welcomed to come and have a good meal. They are free to come and go and nobody is allowed to kill any animal in Canada. They have a law against killing wild animals. If you killed an animal, you would be punished. If an animal happened to get run over by a car, people would be very sad about it.

People in Canada have many reasons to like animals. One of them might be that their family ties are not as close as ours. When children grow up, they leave their parents and start their own life. Then the old will feel lonely, but pets can solve this problem. They can be good friends and never leave them alone.

小题1: The passage mainly talks about____ .

A．how to keep disease from pets

B．pets in Canada

C．how to take good care of pets

D．life of the old in Canada小题2:They give their pets injections before keeping them at their houses because ____.

A．the pets are sick

B．the pets are wild

C．they want to stop them from getting sick

D．they want them to sleep on the way home小题3:In Canada, children leave their parents when they grow up because ____.

A．they don't love their parents any more

B．they can only find jobs far from their parents

C．their parents’ houses are too small

D．they wouldn't depend on their parents any more小题4: Which of the following is TRUE？

A．People buy animal food only at the animal food stores.

B．Pets eat better than people.

C．Almost every family has a birdcage in his house.

D．Any bird can come to the bird feeders to eat.

三硅酸镁可：（）

A．中和胃酸

B．形成聚合物保护黏膜

C．二者皆有

D．二者皆无

描述随机信号必须用概率和统计的方法。