周围型肺癌主要见于哪些组织学类型() A.细支气管肺泡癌 B.腺癌 C.鳞状上皮

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Damage to Ozone layer Gets Worse

In the middle of winter, when snow is falling in many parts of the United States, scientists have sounded a warning to people who plan to spend many hours in the sun this summer. The warning is: The sun’s summertime rays are more dangerous than once thought.

A team of scientists from 80 nations recently reported to the United Nations that a layer of ozone (臭氧层) in the atmosphere, which protects humans from harmful levels of ultraviolet radiation（紫外线辐射）, will be thinner over the United States this summer. The thinner layer allows more ultraviolet rays from the sun to reach Earth. The extra amount of ultraviolet radiation could cause an increase in the number of cases of skin cancer.

Scientists first became concerned about the ozone layer in the mid-1980s when a hole was discovered in the layer above Antarctica during the winter. The hole was caused by chemicals used in refrigerators and air conditioners. When these chemicals are sent out into the atmosphere, they produce gases that destroy the ozone.

Concern about the protective ozone layer rose more recently when data(数据) from satellites and ground stations showed that ozone levels were dropping over areas other than Antarctica. Low ozone levels were recorded in the spring and summer over the United States and over other populated areas in the world.

Although many countries have already begun stopping the use of ozone destroying chemicals, the new findings are expected to advance the timetable for a total ban(禁止) of the chemicals.

59.   The scientists have observed the ozone layer_____.

A.  since 1980             B.  since last winter      

C.  for about 20 years       D.  for about one year

60. The ozone layer in the atmosphere can _____.

A.  do a lot of good to human beings in many ways.

B.  protect humans from diseases caused by bad weather.

C.  do a lot of harm to human beings in the summer-time.

D.  protect humans from harmful levels of ultraviolet radiation.

61. Scientists first found that there was a hole in the ozone layer_____.

A.  above Arctic during the winter in the mid-1980s

B.  above Antarctica during the winter in the mid-1980s

C.  over somewhere in the north of the equator in 1980

D.  over the U.S.A in the summertime in the mid-1980s

62.   The damage to the ozone layer was caused by_____.

A.  the changeable weather

B.  ozone-destroying chemicals

C.  chemicals from refrigerators

D.  chemicals from air conditioners

劳动教养管理所的内部机关科室设置一般分为______。

A．常设机构

B．非常设机构

C．必设机构

D．非必设机构

多见于肾病综合征的管型是（）。

A.颗粒管

B.蜡样管型

C.脂肪管型

D.细胞管型

E.透明管型

导游员每年的考评内容是什么？

营养性饲料添加剂，是指为补充饲料营养成分而掺入饲料中少量或微量物质，包括（）。

A．维生素

B．矿物质

C．酶制剂

D．豆粕