题目内容
（请给出正确答案）
A.marginal cost is minimized
B.social welfare is compromised by overextended resources
C.marginal cost equals average fixed costs
D.marginal cost equals average total cost
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更多“In the long run, all firms in …”相关的问题
The largest footrace in the world is the 12 - kilometer Bay to Breakers race that is held in San Francisco every spring. This race begins on the east side of the city near San Francisco Bay and ends on the west side at the Pacific ocean. In 1993 there were 80, 000 people running in this race through the streets and hills of San Francisco. In the front are the serious runners who compete to win, and who might finish in as little as 34 minutes. Behind them are the thousands who take several hours to finish. In the back of the race are those who wear costumes just for fun. In 1993 there was a group of men all of whom dressed up like Elvis Presley. There was a group of firefighters who were all tied in a long line and were carrying a firehouse. One year there was a bridal (新婚的) party in which the bride dressed in a long white gown and the groom wore a tuxedo (晚礼服). They threw flowers to bystanders, and were actually married at some point along the route.
The main purpose of this passage is to ______.
A．encourage people to run
B．describe a popular activity
C．make fun of runners in costume
D．give reasons for the popularity of footraces
The toothless, or baleen, whales belong to the suborder of Mysticeti. This is a group of generally large whales, formerly abundant in all the oceans of the world. Though reduced by hunting, most species are still found along the coasts of the United Stated and Canada. All but two of the Mysticeti reach 40 feet or more at maturity, with the blue whale running up to 100 feet and tipping the scales at up to 130 tons. This whale is by far the largest creature that has ever lived on earth, 4 times the weight of the largest dinosaur, 30 times that of an elephant.
With what topic is the passage mainly concerned？
A．Breeding habits of whales.
B．Differences between whales.
C．Efforts to preserve whales.
D．The intelligence of whales.
One of the most usual color schemes that helps animals to keep【B10】being seen, is a dark back and light underpants, if an animal is the same color all over, there is always a dark shadow along the animal's belly(腹部). Even if an enemy couldn't see the animal he could see this dark shadow.
【B1】
A．helps
B．contributes
C．tries
D．manages
As used in the last sentence, the phrase "in short" means ______.
A. in the long run
B. in detail
C. in fact
D. in a word
In the long run, and ______ a broad scale, where we live makes us who we are.
A．at
B．in
C．on
D．from
In ancient times, man settled near rivers or on fiver banks and built up large empires.
Water is Nature’s most precious gift to man. Man needs water to irrigate his crops, to cook and to wash. In nations all over the world rivers mean life and wealth. They feed and clothe the nations around them.
Water is also a source of energy and power. Man constructs huge dams across the river to control the water for irrigation and get the energy needed to drive generators. The electrical power is then directed to homes, cities, factories and television stations.
Man uses water each day. His main source of water comes from reservoirs, which in turn get their water from the rivers.
Rivers also bring down soil and minerals from the mountains and deposit them on the plains building up rich fiver deltas for raising plants and crops. Fresh water life in rivers or in lakes fed by them provide man with food.
In a small way rivers help to keep man in good health and provide for his amusements. Various forms of water sports keep man strong and healthy.
Rivers have run on this earth long before man. Man’s future ability to live is uncertain, but rivers will flow on forever.
Rivers have been important to man ______.
A．since the last century
B．for a very long time
C．since a few hundred years ago
D．since a few years ago
In ancient times, man settled near rivers or on river banks and built up large empires.
Water is the Nature's most precious gift to man. Man needs water to irrigate his crops, to cook and to wash. In nations all over the world rivers mean life and wealth. They feed and clothe the nations around them.
Water is also a source of energy and power. Man constructs huge dams across the river to control the water for irrigation and get the energy needed to drive generators. The electrical power is then directed to homes, cities, factories and television stations.
Man uses water each day. His main source of water comes from reservoirs, which in turn get their water from the rivers.
Rivers also bring down soil and minerals from the mountains and deposit them on the plains building up rich river deltas for raising plants and crops. Fresh water life in rivers or in lakes fed by them provide man with food.
In a small way rivers help to keep man in good health and provide for his amusements. Various forms of water sports keep man strong and healthy.
Rivers have run on this earth long before man. Man's future ability to live is uncertain, but rivers will flow on forever.
Rivers have been important to man______.
A．since the last century
B．for a very long time
C．since a few hundred years ago
D．since a few years ago
The phrase“in the long run”（Paragraph 3）is closest in meaning to“__________ ”．
A.in pmctice
B.in the end
C.in effect
D.in no time
In ancient times, man settled near rivers or on river banks and built up large empires.
Water is Nature's most precious gift to man. Man needs water to irrigate his crops, to cook and to wash. In nations all over the world rivers mean life and wealth. They feed and clothe the nations around them.
Water is also a source of energy and power. Man constructs huge dams across the river to control the water for irrigation and get the energy needed to drive generators. The electrical power is then directed to homes, cities, factories and television stations.
Man uses water each day. His main source of water comes from reservoirs, which in turn get their water from the rivers.
Rivers also bring down soil and minerals from the mountains and deposit them on the plains building up rich river deltas for raising plants and crops. Fresh water life in rivers or in lakes fed by them provide man with food.
In a small way rivers help to keep man in good health and provide for his amusements. Various forms of water sports keep man strong and healthy.
Rivers have run on this earth long before man. Man's future ability to live is uncertain, but rivers will flow on forever.
Rivers have been important to man ______.
A．since the last century
B．for a very long time
C．since a few hundred years ago
D．since a few years ago
