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Investigators have not yet _______ the cause of the air crash.
A. determined
B. explored
C. devised
D. hastened
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更多 “ Investigators have not yet _______ the cause of the air crash. A. determinedB. exploredC. devisedD. hastened ” 相关考题
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Have they decided on the ______ of the new building yet?
A. locateB. localC. locatedD. location
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I _____my breakfast at 8, but_____ I lunch yet. .A. had, haven't hadB. had, didn't haveC. have had, didn't have
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We ( ) on it for many hours but we have not yet reached any conclusion.
A、have had workedB、have been workingC、are workingD、work
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Air pollutionPeople and air pollution are often in the same places. This means that cities with large populations have the biggest problem of dirty air. Air pollution is caused by many different things. A major kind of air pollution is the gas from cars. Statistics(统计资料) show that 93 percent of all auto trips are within cities.Another major kind of dirty air is the burning of coal and oil for energy. This energy is needed to make electricity. Of course, much more electricity is used in the city than in the county.On the average, we throw away more rubbish than the year before. The burning of rubbish makes air pollution even worse. Many major industries are also responsible for the dirty air in the around cities. The fumes(烟)from iron, steel, chemical, and petrol production add particles(微粒)to the air.The effects of air pollution range from mild headaches to death. The levels of pollution found in heavy traffic may cause headaches for loss of clear vision. Wherever coal and oil are used for fuel, fumes may kill trees and plants and cause metal to corrode(腐蚀). In some of the larger cities, these fumes endanger the lives of human beings by contributing to lung diseases and causing early death.26. The key point of the passage is that().A. the cause of air pollution is peopleB. the causes and the effects of air pollution are both found in citiesC. the effects of air pollution range from headaches to death27. What is the purpose of this passage?A. to persuade people to stop polluting the air().B. to tell the causes of air pollutionC. to tell why cities are bad places to live28. Why is air pollution more grave in the city than in the country?().A. Because there are larger populations in cities.B. Because the air in the city is dirty.C. Because there are much more gas fumes from cars and burning of coal and oil for energy in the city than in the country.29. The fumes from coal and oil may cause metal().A. to corrodeB. to twistC. to turn black30. In larger cities, the fumes from coal and oil may contribute to().A. heart diseaseB. loss of clear visionC. lung diseases
考题
If the engine does start on air, but combustion does not immediately begin, the cause may be _____.A.failure of the fuel pumpsB.starting air pressure too lowC.stop valve in air line closedD.the turning gear still engaged
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What is the most probable cause of reduced capacity in a reciprocating air compressor ________．A.Carbon on cylinder headsB.Faulty unloaderC.Leaking air valvesD.Plugged air cooler
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__________enough time and money, the investigators would have been able to discover more evidence in this case.
A．Giving
B．Given
C．To give
D．Being given
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If headaches only occur at night,lack of fresh air is often the cause.A:start B:begin C:happen D:visit
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If headaches only occur at night,lack of fresh air is often the cause.A:start B:begin C:happen D:visit
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Have you installed the new software?（）A、Installed.B、Uninstalled.C、No, not yet.D、Yes, not yet.
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单选题Broken valve strips in an operating low pressure, air compressor will cause （）.A
an immediate crankcase explosionB
oil contamination in the compressed airC
a decrease in compressor capacityD
no immediate loss of the compressed air capacity
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单选题The text suggests that investigators of monkeys’ social behavior have been especially interested in aggressive behavior among monkeys because ______.A
aggression is the most common social behavior among monkeysB
successful competition for incentives determines the social order in a monkey groupC
situation that elicit aggressive behavior can be studied in a laboratoryD
most monkeys are potentially aggressive, yet they live in social units that could not function without control of their aggressive impulses
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单选题Air bubbles in a hydraulic governor can cause （）A
sluggish responseB
speed droop variationsC
isochronous governingD
sensitivity increase
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单选题Which of the following may cause that an engine doesnt turn on starting air?（）A
too low starting air pressureB
main starting valve closedC
neither A nor BD
A and B
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单选题Which cause of the following can lead to the engine not to start on air?（）A
starting air pressure too highB
correct timing of starting air valvesC
three of the starting valves stuckD
the turning gear disengaged
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单选题Which of the following problems could cause air to blow out through the inlet air filter of a running compressor?（）A
Excessive compression in the cylinderB
A broken intake valveC
A dirty inlet filter elementD
An improperly adjusted discharge valve
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单选题If over a period of weeks the air-box pressure of a turbo-charged, diesel engine, operating at full load, appears to be dropping off, the cause can be （）.A
open air-box drainsB
loss of cooling water to the diffuserC
gradual fouling of the air filtersD
improperly timed exhaust valves
考题
单选题_____A
Many people died in a fire.B
Two persons were injured.C
There was a traffic accident.D
There was an air crash.
考题
单选题In context, which version of the underlined part of sentence 3 (reproduced below) is the best?Baby lobsters are preyed on by fish and crabs because they don't have a hard shell yet and can't defend themselves with fierce claws yet.A
the lobsters still lack both hard shells and fierce claws with which to fend off predatorB
the lobsters cannot attack their fish and crab predators with fierce claws or fend their predators off with a hard shellC
they don't have a hard shell yet and can't defend themselves with fierce claws yetD
the lobsters don't have a hard shell and can't yet defend themselves with fierce clawsE
the fish and crabs do not have hard shells or fierce claws yet
考题
单选题Exhaust temperature increases in all cylinders, the possible cause may be（） (1) increased scavenging air temperature (2) air in fuel pumps and fuel valves (3) fouling of air and gas passagesA
(1)+(2)B
(1)+(3)C
(2)+(3)D
(1)+(2)+(3)
考题
单选题Disastrous explosions have been caused by accumulations of oil or oil vapour in air lines not drainedAccording to the above sentence, which of the following statements is true?（）A
Oil vapour in air piping are dangerousB
Explosion will cause oil vapouring in air linesC
Oil vapour in air piping should be drainedD
Oil in air piping should not be drained
考题
单选题When starting air is admitted, a diesel engine turns over very slowly without firingThe cause may be （）A
an obstruction in an cylinderB
water accumulation in some engine cylindersC
low starting air pressureD
low scavenge air pressure
考题
单选题Unless the conservator can find a way to protect the photographs in the archives from light and air, these precious historical documents have deteriorated and will continue to do so both in color and in fine detail.A
have deteriorated and will continue to do soB
will continue to deteriorateC
have been and will continue to deteriorateD
will continue to deteriorate, as they already have,E
will be deteriorating yet more
考题
单选题If the engine does start on air, but combustion does not immediately begin, the cause may be （）.A
failure of the fuel pumpsB
starting air pressure too lowC
stop valve in air line closedD
the turning gear still engaged
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