Ⅱ型呼吸衰竭患者维持呼吸中枢的兴奋主要依靠（） A.CO2对呼吸中枢的刺激 B.CO

只有正确分析__________，才能找到应对挫折的方法。另外，也要发扬自己的______，从而振奋精神，鼓起战胜挫折的勇气，树立信心，提高对挫折的承受能力。

阅读理解。

     The African ancestors of today's black Americans were brought

to the US as slaves in the seventeenth, eighteenth, and nineteenth

century, They worked on farms, especially the large farms in the

southern states. Slowly they became a necessary part of the economic

system (经济体系) of the South.

      Slaves did not have the right of people;according tO the law,

they were a" thing" which belonged to the person who bought them.

They had to obey the orders of their owners without question. They

were not allowed to learn to read ; their owners feared the educated

slaves would begin to think about the injustice of the system and

would learn to struggle for their freedom. Slaves had to work long

hours in very unhealthy conditions. Their owners had complete power

over them. They could be bought and sold like animals. At the

slave markets, black children were separated from their parents and

never saw them again. Slave owners had the right to punish the

slave who broke the rule or was against the system. Slaves were often

beaten by their owners or killed. After the Civil War, one free

slave reported that his owner killed an older slave who was teaching

him to read. In theory, an owner who treated a slave badly could be

punished. In practice, however, the taw meant nothing.

      The opposition to slavery began very early in the history of the

US-in 1671-but little progress was made until the beginning of

the nineteenth century. By 1804, slavery was illegal in the northern

states. But it continued and even grew, in the southern states, which

depended on cotton for their economic health. Slavery ended in the

South only after the Civil War. For blacks,however,the end of slavery

was only a beginning, the beginning of a long and difficult struggle for

true justice.

1. What is the main topic of this passage?    

A. African ancestors of today's black Americans.

B. The opposition to slavery in the United States.

C. Slavery in the United States.

D. The right of black Americans.

2. According to the writer,why couldn't slaves learn to read?   

A. Because reading was not something which they needed for their work.

B. Because their owners were afraid that books would give them advanced ideas.

C. Because they did not have enough time to read.

D. Because they were so poor that they could not go to school.

3. Which of the following can be inferred from the passage?  

A. Many people from other countries became US citizens in the 1700s.

B. The US government paid much attention to freedom.

C. There were some laws that successfully protected the rights of slaves.

D. The opposition to slavery in the United States began in the seventeenth century.

翻译：子曰：“非其鬼而祭之，谄也。”。

停止运行多长时间的变压器，在重新投入运行前需测绝缘电阻及做油的耐压试验？（）

A.一个月

B.三个月

C.六个月

D.一年

软流圈包括在（）

A、地壳中，

B、上地幔中，

C、下地幔中，

D、地核中