An increase in the money supply causes output to rise in the long run.

用IS-LM图描述下列变动对国民收入、利率、物价水平、消费、投资以及实际货币余额的短期与长期影响。

  a．货币供给增加。

  b．政府购买增加。

  c．税收增加。

  Use the IS-LM diagram to describe the short-run and long-run effects of the following changes on national income, the interest rate, the price level, consumption, investment, and real money balances.

  a．An increase in the money supply.

  b．An increase in government purchases.

  c．An increase in taxes.

A、decrease; decrease.

B、decrease; increase.

C、increase; decrease.

D、increase; increase.

In the past, American families tended to be quite large. Parents raising five or more children were common. Over the years, the size of the family is becoming smaller. One reason for this is an increase in the cost of living.

Generally children attend schools for more years than they used to, making them financially dependent on their families longer. Moreover, children nowadays are better dressed and have more money to spend on entertainment. The parents are usually responsible for all the expenses. And families are less close than they used to be. More and more American mothers work away from home. The break-up of the family appears when the parents' divorce.

A lot of children in the U. S. live part of their young lives with only one parent. Children grow up feeling unsettled as they are moved between their parents. Single parents often marry other single parents. In this type of family, unrelated children are forced to develop brother or sister relationship.

The situations of many American families today are not good. However, recent signs show that things are getting better. The divorce rate is declining(降低). Perhaps Americans have learned how important families are.

21. In the past, American families tended to be().

A. quite small

B. medium sized

C. quite large

22. To parents who take the responsibility for children's expenses, the cost of living increases because().

A. children attend school for more years

B. children are better dressed and spend more money on entertainment

C. all of the above

23. Children whose parents divorced always feel unsettled because().

A. they are moved between their parents

B. they are forced to develop brother or sister relationship

C. they have little money to spend

24. According to the author, the situations of American families in the future may().

A. get better

B. remain the same

C. become worse

25. The title of the article might be() .

A. American Children

B. American Families

C. American Parents

For the long run variance-covariance estimator=()(j)， when n is large enough, we can let= [], where [x] is the largest integer that is not greater than X.