采用哥特式弓描记法，当描记针指向图形顶点时下颌恰好处于（） A.正中（牙合）位 B.

主链为4个碳原子的己烯共有几种结构

A．2种

B．3种

C．4种

D．5种

Many of the world’s pollution problems have been caused by the crowding of large groups of people into the cities. Supply for the needs of the people leads to further pollution by industry. If the rapid increase of world population in countries continues at the present rate, there may be much greater harm to human beings. Some scientists speak of the increase in numbers of people as “population pollution.”

About 2,000 years ago, the world population was probably about 250 million. It reached a billion in 1850. By 1930 the population was two billion. It is now three and a half billion. It is expected to double by the year 2,000. If the population continues to grow at the same rate, there will be 25 billion in the world a hundred years from now.

Man has been using the earth’s resources more and more rapidly over the past years. Some of them are almost used up. Now many people believe that man’s greatest problem is how to control the growth of the population. The material supplies in the world will be far from enough to support the human population, in time to come, if the present rate of increase continues. Already there is overcrowding in many cities and starvation in some countries. Should man’s population keep on growing so rapidly as before? Many people believe that human survival in the future depends on the answer to this question.

59. The rapid increase in population is considered to be __________.

A. the increase of resources          B. population pollution

C. the development of mankind       D. the present rate

60. The world population will be _________ by the year 2,000.

A. 7 billion                  B. 250 million       C. 25 billion      D. 3.5 billion

61. If the present rate of increase continue, ________________.

A. the world is going to end

B. the earth won’t be able to support the growing population in the future

C. pollution has nothing to do with the rapidly increasing population

D. there would be four billion in the world a hundred years from now

62. Which of the following is WRONG according to the passage?

A. In 1850 the world population reached a billion.

B. Man must fight a battle against population pollution.

C. The world’s population is increasing with years.

D. All of the earth’s resources are gone now.

按1岁为一个年龄组编制而成的寿命表称为（）

A.寿命表

B.定群寿命表

C.现时寿命表

D.完全寿命表

E.简略寿命表

男性，50岁。近1周间断性便血，伴肛门坠胀感。首先应进行（）。

A.直肠指检

B.乙状结肠镜检查

C.大便潜血试验

D.纤维结肠镜检查

E.肛门镜检查

应税消费品的全国平均成本利润率由（）确定。

A、财政部

B、国家税务总局

C、国务院

D、国家税务总局所属征收机关