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The problem of municipal sewage disposal is complicated by the fact that, years ago, most cities combined their storm and waste disposal sewers. Many of these combined systems work well, but others cannot cope with sudden heavy rains. When such storms occur, water mixed with sewage may flood and disable treatment plants unless bypassed, untreated, into a stream. In either case, the people may have little protection for several days from these wastes that may contain disease germs.
One consequence of pollution, usually resulting from the discharge of either raw or treated sewage wastes into water sources, is an increase in nutrient levels in these waters. These higher nutrient levels result in a rapid increase in the biological population of the water. Excessive respiration and decomposition of aquatic plants deplete the oxygen content in these waters causing decay which, in turn, may produce an undesirable taste, odor, color and turbidity. Increasing nutrient contents may also result in an in- crease in more undesirable species of aquatic life. All these factors make the water un- fit for domestic, industrial and recreational purposes.

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Mental health is our birthright. (46) We don’t have to learn how to be mentally healthy ;it it built into us that our bodies know how to heal a cut or mend a broken bone. Mental health can’t be learned, only reawakened. It is like the immune system of the body, which under stress or through lack of nutrition or exercise can be weakened, but which never leaves us. When we don&39;t understand the value of mental health and we don&39;t know how to gain access to it, mental health will remain hidden from us.
(47) Our mental health doesn’t really go anywhere; like the sun behind a cloud, it can be temporarily hidden from view, but it is fully capable of being restored in an instant. Mental health is the seed that contains self-esteem - confidence in ourselves and an ability to trust in our common sense. It allows us to have perspective on our lives - the ability to not take ourselves too seriously, to laugh at ourselves, to see the bigger picture, and to see that things will work out. It’s a form. of innate or unlearned optimism.
(48) Mental health allows us to view others with sympathy if they are having troubles ,with kindness if they are in pain,and with unconditional love no matter who they are. Mental health is the source of creativity for soving problems, resolving conflict, making our surroundings more beautiful,managing our home life, or coming up with a creative business idea or invention to make our lives easier. It gives us patience for ourselves and toward others as well as patience while driving,catching a fish,working on our car,or raising a child. It allows us to see the beauty that surrounds us each moment in nature,in culture,in the flow of our daily lives.
(49) Although mental health is the cure-all for living our lives,it is perfectly ordinary as you will see that it has been there to direct you through all your difficult decisions.It has been available even in the most mundane of life situations to show you right from wrong,good from bad,friend from foe.Mental health has commonly been called conscience,instinct,wisdom,common sense,or the inner voice.We think of it simply as a healthy and helpful flow of intelligent thought .
(50) As you will come to see ,knowing that mental heath is always available and knowing to trust it allow us to slow down to the moment and live life happily.
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A 卧床休息
B青霉素消除感染灶
C氢氯噻嚷利尿降压
D大剂量糖皮质激素和免疫抑制剂

1 In 1959 Americans welcomed Alaska into the Union as the 49th state, symbolizing a change of attitude from that held in 1867, when the peninsula was purchased from Russia. Then, most Americans had little interest in 1,500,000 square kilometers "of icebergs and polar bears" - beyond Canada's western borders, far from the settled areas of the United States.
2 In those sections of the state which lie above the Arctic Circle, Alaska still is a land of icebergs and polar bears. Ice masses lie buried in the earth, which is permanently frozen to a depth of 90 or more meters. From early May until early August, the midnight sun never sets on this flat, treeless region, but the sun cannot melt the icy soil more than two - thirds of a meter down.
3 Alaska is America's largest state, but only about 325,000 people live there. According to estimates, 800,000 hectares of its land area are fit for plowing but only about 640,000 hectares are being cultivated.
4 Arctic Alaska has been the home of Eskimos for countless centuries. It is believed that the Eskimos moved there from Mongolia or Siberia, probably crossing Bering Strait, named for Vitus Bering, the Danish sea captain who discovered Alaska on his voyage for Russia in 1741. The Eskimos are the state's earliest known inhabitants5. Russian fur traders established settlements but, by the time Alaska was sold to the United States, most of the traders had departed.
5 In 1896 gold was discovered near the Klondike River in Canada just across the Alaskan border. Thousands of Americans rushed to the region on their way to Klondike; some never returned. Alaska was never completely cut off again, although even today transportation is a major problem. There are only two motor routes from the US mainland, and within the state, every town has its own airfield. Planes fly passengers, mail and freight to the most distant villages.
6 The gold that changed life so suddenly for Alaska was soon ended, and although many stories about mining camps have become part of American literature, the gold from Alaskan earth contributed less to economic progress than the fish from Alaskan waters. The fish caught in a single year range in value from $80 million to $90 million. Fur-bearing animals are plentiful in the forests and streams, and valuable fur seals inhabit the waters. After fishing, the state's chief industry is lumber and the production of wood pulp. In recent years, Alaska's single most important resource has become oil. The state also has large deposits of coal, copper, gold and other minerals.
A Rich Resources of the State
B Connections with the Outside World
C Transportation Problem
D The Natives of the Land
E Cold Climate
F Land and Population
Paragraph 3 ______

①Noam Chomsky
②M.A.K. Halliday
③Sigmund Freud
④John B. Watson
⑤Leonard Bloomfield
B: the theory he advocates
a. American structuralism
b. transformational generative linguistics
c. functional linguistics
d. psychoanalysis
e. behaviourism
①