问题 选择题

在一定温度和压强下的理想气体,影响其所占体积大小的主要因素是

A.分子直径的大小

B.分子间距离的大小

C.分子间引力的大小

D.分子数目的多少

答案

答案:D

由于气体分之间的距离远大于气体分子直径大小,所以在一定温度和压强下的气体分子之间的距离都近乎是相等的,因此影响其所占体积大小的主要因素是分子数目的多少,答案选D。

单项选择题
阅读理解

阅读理解。

      Today, we have a world economy. Canadian businesses and workers must compete with businesses

and workers in other countries.

      Every year, more Canadian factories are closing or moving. They cannot compete with factories in

countries where wages (工资) are low. In the future, there will be fewer jobs for factory workers in

Canada.

      Many Canadian businesses are trying to spend less money. For example, they are hiring more part-time

workers and more temporary (临时的) workers. They are employing fewer permanent (永久的) full-time

workers. More services, fewer goods. Canada's economy is changing. Businesses are making fewer goods

(for example: shoes and radios). But Canadian businesses are providing more services to people. 

      In the future, there will be more jobs for people who provide services. For example: sales people, waiters

and waitresses, home health care workers, bakers and cooks.

      There will be fewer jobs for other kinds of workers (for example: farmers, miners, fishermen, forestry

workers and factory workers). Many new jobs will be in small businesses with 20 or 30 employees.

Technology machines are changing the way people work.

      Business are using many machines (for example: computers and robots). Businesses will need fewer

workers. And some jobs will disappear. Many grown-ups will have to go back to school or train for new

jobs. Workers will not stay in the same job for their lifetime. The population of Canada is changing.

      Today, many Canadians are in their 30s and 40s. They need goods and services. As they get older, they

will need different goods and services.

      Canadians come from many cultures. They have different customs and religions. Employers and workers

must learn to work with many different people.

1. World economy means ______ to Canada. [ ]

A. closing and moving

B. competition

C. low wages

D. improvement

2. Which of the following will be fewer in the future in Canada? [ ]

A. Restaurants

B. Shops

C. Doctors

D. Farmers

3. Businesses will need fewer workers because ______.[ ]

A. the owners can't afford them

B. some jobs will disappear

C. machines will take the place of workers in many ways

D. the workers will have to be trained for new jobs

4. Which of the following statements is TRUE? [ ]

A. Many people who come from different cultures will work together.

B. All Canadians have the same culture and religion.

C. Different cultures will do good to Canada.

D. Many Canadians will change their jobs in the future.