宇宙飞船进入一个围绕太阳运动的近乎圆形的轨道上运动，如果轨道_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

宇宙飞船进入一个围绕太阳运动的近乎圆形的轨道上运动，如果轨道半径是地球轨道半径的9倍，那么宇宙飞船绕太阳运行的周期是（　　）

A．3年

B．9年

C．27年

D．81年

答案

开普勒第三定律中的公式

R3

T2

=K

解得：T=

R3

K

一颗小行星围绕太阳在近似圆形的轨道上运动，若轨道半径是地球轨道半径的9倍，

小行星绕太阳运行的周期是地球周期的27倍，即小行星绕太阳运行的周期是27年．

故选C．

选择题

下列说法中正确的是

A．离子化合物中可以含有共价键，但共价化合物中一定不含离子键

B．含有共价键的物质一定是共价化合物

C．分子中一定含有化学键

D．含有金属元素的离子一定是阳离子

填空题

Part 4

Questions 26-45

·Read the following passage and decide which answer bestfits each space.
·For questions 26-45, mark one letter A, B, C or D on the Answer Sheet.
The "standard of living" of any country means the (26) person’s share of the goods and services which the country produces. A country’s standard of living, therefore depends (27) and foremost on its capacity to produce wealth. "Wealth" in this (28) is not money, for we do not live on money (29) on things that money can buy: "goods" such as food and clothing, and "services" such as (30) and "entertainment".
A country’s capacity to produce wealth depends upon many factors, most of which have an effect (31) one another. Wealth depends (32) a great extent upon a country’s natural resources. Some regions of the world are well supplied with coal and minerals, and have a (33) soil and a favorable climate; other regions (34) none of them.
Next to natural resources (35) the ability to turn them to use. China is perhaps as well off as the USA in natural resources, but suffered for many years from (36) and external wars, and for this and other reasons was incapable (37) her resources. Sound and (38) political conditions, and freedom from foreign invasion, enable a country to develop its natural resources peacefully and steadily, and to produce more wealth than another country (39) well served by nature but less well ordered.
A country’s standard of living does not only depend upon the wealth that is produced and (40) within its own borders, but also upon what is indirectly produced through international trade. For example, Britain’s wealth in foodstuffs and other agricultural products would be much (41) if she had to depend only on those grown at home. Trade makes it possible for her surplus manufactured goods to be traded abroad for the agricultural products that would (42) be lacking. A country’s wealth is, therefore, much (43) by its manufacturing capacity, (44) that other countries can be found ready to (45) its manufactures.

A．little

B．less

C．much

D．more