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单选题 nullA kite is held in the air when the push of the air on the underside of the kite is greater than the push of the air on the upper side. The difference in push is controlled by the wind. An aircraft stays in the air for the same reason, except that it has to keep moving rapidly to maintain this difference in air pressure above and below its wings. A kite flies because of the wind; a plane flies because of its ______
学科：工程学科英语
时间：2023-06-26 05:32:32
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题目1单选题
A very secure form of communication is furnished by wires, but it requires time to set up the wires, and they can get out of order. Telephone lines involve a great deal of maintenance. The wires are often buried in the ground so that there will be ______A. more wireB. less interruption to serviceC. fewer bad stormD. more open skylines
题目2单选题
For years engineers had dreamed of building a suspension bridge spanning the entrance to New York Harbor. In 1964 that dream was realized as the record-breaking span of 1298 meters neared completion. The engineer who designed the bridge was almost sorry because now engineers would not have that bridge to dream about. But engineers were already planning for bridges with spans of ______A. 649 metersB. 1000 metersC. 2500 metersD. unlimited length
题目3单选题
nullA kite is held in the air when the push of the air on the underside of the kite is greater than the push of the air on the upper side. The difference in push is controlled by the wind. An aircraft stays in the air for the same reason, except that it has to keep moving rapidly to maintain this difference in air pressure above and below its wings. A kite flies because of the wind; a plane flies because of its ______A. massB. directionC. motionD. pilot
题目4单选题
In 1785, the French aeronaut, P. Blanchard successfully used a parachute to drop a dog in a basket to the ground from a balloon high in the air. In 1793, Blanchard himself used a parachute to jump from a balloon. His first attempt was not successful — he broke his leg. Others made several attempts, some successful, some not, before parachute jumping came to be common and ______A. dangerousB. safeC. martialD. expensive
题目5单选题
The preparations for sending an animal into a place were very elaborate. Such a project was not attempted until the scientists were sure that they had taken care of every detail and that the risk to the animal in flight was ______A. fearedB. providedC. minimalD. concerned
题目6单选题
Copper is a fairly soft metal and is easily shaped even when it is cold. It was one of the first metals used in making tools. Copper relics have been found that are older than recorded history. Copper is more extensively used than any other metal except iron. Fortunately, it is not ______A. malleableB. availableC. expensiveD. plentiful
题目7单选题
An experimental jet plane was designed to fly at speeds of over 3000 kilometers per hour and altitudes as high as about 27000 meters. At this speed, the temperature of the plane's surface would rise to 315 degrees Celsius. If the plane were not built both inside and outside to withstand this drastic change in temperature, the plane and its crew would ______A. bail outB. freeze solidC. fly at nightD. burn to a crisp
题目8单选题
There are a number of nuclear power plants now built or under construction by the government and by investor-owned power companies. Although most of the electricity used in the world is generated in steam or hydroelectric power plants, nuclear plants will help to meet increasing demands for ______A. electrical appliancesB. safe investmentC. weapons researchD. electric power
题目9单选题
Iron is produced commercially on every continent and on many islands. The United States is one of the major producers of iron. Although some metals seem more valuable, iron is the most important metal in the world. The great industrial development of the United States has made use of tremendous quantities of iron. It is fortunate that its domestic supply is so ______A. expensiveB. largeC. deepD. localized
题目10单选题
Magnesium, a very useful metal, is abundant in the earth. The greatest source of magnesium, however, is not the earth but the oceans. Processes have been developed to economically extract magnesium from seawater. This makes the valuable metal readily available to countries that border the oceans. Magnesium is available to most countries either from the sea or from the ______A. oceansB. landC. riversD. mountains
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