通常所说柴油机的固定部分（骨架）是指（）。A、机体组件 B、汽缸套 C、汽缸盖 D、油底壳

据北京某一中学生在保险公司投保人身意外伤害保险，交付保险费5元，保障期一年。后来，该生因意外交通事故受伤，住院3个月，花费医疗费用7000多元，经核定，按照保险合同的约定，保险公司付给该生保险金额3800元。

请回答：

(1)商业保险的作用是什么?

(2)商业保险是否比储蓄优越?为什么?

Silk production has a long and colourful history unknown to most people. Scientific discoveries have shown that silk production existed in China from around 2500 B.C., although it could be much older. For hundreds of years, China kept the secret of silk to itself as one for the most closely protected secrets in history. Anyone revealing the secret of silkworms or trying to take silkworm eggs out of ancient China was punished by death.

At one time silk was reserved only for the Chinese emperor. Gradually, others began wearing silk. In addition to being used for clothing, silk came to have industrial uses in ancient China, something that happened in the West only in modern times. Silk was used to make musical instruments, fishing lines, weapons, ropes and even paper. During the Han Dynasty silk became a form of money. Farmers paid taxes in both rice and silk. The prices of goods were calculated in lengths of silk just as they had once been calculated in gold. The importance of silk is even reflected in the Chinese language. For example, of the 5000 most common Chinese characters, around 500 have silk as their “key”.

In spite of their secrecy, the Chinese eventually lost their monopoly on silk production. It reached Korea in around 200 B.C. when immigrants from China arrived there. Silk production came to India in 300 A.D.. It was not until 500 A.D. that silk production came to Europe when travellers smuggled out silkworms in hollow tubes of bamboo. These were used to establish silk industry in Rome (modern-day Italy), although Chinese silk was still considered to be the best.

Silk was brought to Rome from China by means of the Silk Road. There were actually two Silk Roads, one over land and one on the sea. The land route in particular had a huge effect in history. All sorts of trade goods — silver, gold, jade, porcelain — passed along this road. Ideas travelled the Silk Road too. For example the religion of Buddhism was carried to China from India by traders on the Silk Road. The Silk Road created the first international culture, exposing many people to the ideas and treasures of both Western and Chinese cultures.

小题1:How was China able to keep the secret of silk production?

A．It refused to sell its silk to other countries.

B．Foreigners were not permitted to enter China.

C．The silkworms needed were not able to survive outside China.

D．Chinese passing on the secret to foreigners were seriously punished.小题2:Which of the following uses of silk is NOT mentioned in the passage?

A．A way of purchasing goods people sold.

B．A material used for making different products.

C．A method of paying money to the government.

D．A valuable gift given to foreigners travelling in China.小题3:In what order did silk production spread throughout the world according to the passage?

A．Europe àIndia àKorea àChina.

B．China àKorea àIndia àEurope.

C．China àIndia àKorea àEurope.

D．China àEurope àIndia àKorea.小题4:The underlined phrase “smuggled out” in Paragraph 3 is closest in meaning to ________.

A．quietly traded

B．openly removed

C．illegally transported

D．violently stole小题5:Which of the following is true about the Silk Road?

A．It allowed for economic and cultural exchanges between countries.

B．It made China the most powerful country in the ancient world.

C．It could only be completed by travellers with access to a boat.

D．It was first developed for transferring religious ideas.

巷道维修工作应由里向外逐段依次进行

热电阻温度变送器无显示时应检查：（）

A、检查热电阻的接线；检查热电阻的型号是否正确；检查供电电压是否正确

B、检查热电阻的接线；检查热电阻的型号是否正确；校验热电阻温度变送器

C、检查电源的极性是否接反；检查变送器的电路板工作是否正常

D、检查变送器是否送电；检查热电阻的接线；检查校验仪表工作是否正常

N的固定作用