托福阅读TPO18(试题+答案+译文)第3篇:Lightning
TPO是我们常用的托福模考工具，对我们的备考很有价值，下面小编给大家带来托福阅读TPO18(试题+答案+译文)第3篇:Lightning。
托福阅读原文
【1】Lightning is a brilliant flash of light produced by an electrical discharge from a storm cloud. The electrical discharge takes place when the attractive tension between a region of negatively charged particles and a region of positively charged particles becomes so great that the charged particles suddenly rush together. The coming together of the oppositely charged particles neutralizes the electrical tension and releas a tremendous amount of energy, which we e as lightning. The paration of positively and negatively charged particles takes place during the development of the storm cloud.
【2】The paration of charged particles that forms in a storm cloud has a sandwich-like structure. Concentrations of positively charged particles develop at the top and bottom of th
e cloud, but the middle region becomes negatively charged. Recent measurements made in the field together with laboratory simulations offer a promising explanation of how this structure of charged particles forms. What happens is that small (millimeter-to centimeter-size) pellets of ice form in the cold upper regions of the cloud. When the ice pellets fall, some of them strike much smaller ice crystals in the center of the cloud. The temperature at the center of the cloud is about -15℃ or lower. At such temperatures, the collision between the ice pellets and the ice crystals caus electrical charges to shift so that the ice pellets acquire a negative charge and the ice crystals become positively charged. Then updraft wind currents carry the light, positively charged ice crystals up to the top of the cloud. The heavier negatively charged ice pellets are left to concentrate in the center. This process explains why the top of the cloud becomes positively charged, while the center becomes negatively charged. The negatively charged region is large: veral hundred meters thick and veral kilometers in diameter. Below this large, cold, negatively charged region, the cloud is warmer than -15℃, and at the temperatures, collisions between ice crystals and falling ice pellets produce positively charged ice pellets that then populate a small region at the ba of the cloud.
到底要不要生二胎
【3】Most lightning takes place within a cloud when the charge paration within the cloud collaps. However, as the storm cloud develops, the ground beneath the cloud becomes positively charged and lightning can take place in the form of an electrical discharge between the negative charge of the cloud and the positively charged ground. Lightning that strikes the ground is the most likely to be destructive, so even though it reprents only 20 percent of all lightning, it has received a lot of scientific attention.
【4】Using high-speed photography, scientists have determined that there are two steps to the occurrence of lightning from a cloud to the ground. First, a channel, or path, is formed that connects the cloud and the ground. Then a strong current of electrons follows that path from the cloud to the ground, and it is that current that illuminates the channel as the lightning we e.
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【5】The formation of the channel is initiated when electrons surge from the cloud ba toward the ground. When a stream of the negatively charged electrons comes within 100 meters of the ground it is met by a stream of positively charged particles that comes
up from the ground. When the negatively and positively charged streams meet, a complete channel connecting the cloud and the ground is formed. The channel is only a few centimeters in diameter, but that is wide enough for electrons to follow the channel to the ground in the visible form of a flash of lightning. The stream of positive particles that meets the surge of electrons from the cloud often aris from a tall pointed structure such as a metal flagpole or a tower. That is why the subquent lightning that follows the completed channel often strikes a tall structure.
还带
【6】Once a channel has been formed, it is usually ud by veral lightning discharges, each of them consisting of a stream of electrons from the cloud meeting a stream of positive particles along the established path. Sometimes, however, a stream of electrons following an established channel is met by a positive stream making a new path up from the ground. The result is a forked lightning that strikes the ground in two places.
托福阅读试题
1.According to paragraph 1, all of the following take place in the development of a flash of
点石成金的故事lightening EXCEPT
A.great tension between two oppositely charged regions.
B.an increa in negatively charged particles over positively charged particles.
C.oppositely charged particles coming together.
D.the relea of electrical energy in the form of visible light.
2.The word “tremendous” in passage 1 is clost in meaning to
A.distinct.
B.growing.
C.huge.
D.immediate.
3.According to paragraph 2, what caus ice crystal to become positively charged?
A.Collisions with ice pellets.陈寅恪读音
B.Collisions with negatively charged ice crystals at the ba of the cloud.
C.Becoming concentrated in the central region of the cloud.
D.Forming at a temperature greater than -15℃.
4.The word “acquire” in passage 2 is clost in meaning to
A.reject.
B.obtain.
C.need.
D.produce.
结婚酒席
5.According to paragraph 2, why are positively charged ice pellets produced in the lower part of the cloud?
打方向盘A.Collisions between ice crystals and ice pellets increa in number in the lower part of the cloud.
B.The lower part of the cloud is smaller than the region above it.
C.More ice pellets than ice crystals reach the lower part of the cloud.
D.Temperature in the lower part of the cloud are warmer than -15℃.
