托福阅读事实信息题是阅读考试中比较常见的一种题型，tpo则是托福阅读备考最权威的材料，所以托福小编综合二者，为大家集中整理了tpo阅读中考察的事实信息题及其对应的解析，供大家参考使用。本文带来的是TPO18-3的事实信息题，一起来看看吧。
TPO18-3 Lightning
paragraph 2.
The separation 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 the 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 these 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 causes 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: several hundred meters thick and several kilometers in diameter. Below this large, cold, negatively charged region, the cloud is warmer than -15℃, and at these temperatures, collisions between ice crystals and falling ice pellets produce positively charged ice pellets that then populate a small region at the base of the cloud.
3. According to paragraph 2. what causes ice crystals to become positively charged?
Collisions with ice pellets
Collisions with negatively charged ice crystals at the base of the cloud
Becoming concentrated in the central region of the cloud
Forming at a temperature greater than -15℃
解析：以ice crystal和positively charged做关键词定位至第七句，说在这样的温度下，ice pellet和ice crystal的碰撞转移了电荷，使得pellet带负电，crystal带正电，所以答案应该是A碰撞;B虽然也说到碰撞，但不是和负电碰撞;D的温度不是带正电的决定条件
【2】形成雷雨云的带电粒子的分离具有一种三明治结构。带正电的粒子聚集在云的顶部和底部，但是中间区域形成的是带负电的粒子。近期的野外测量以及实验室模拟为这种带电粒子的排列结构提供了可能的解释。实际上在此过程中在云层较冷的上部区域形成了细小的(毫米到厘米大小)冰丸。当这些冰丸飘落时，一部分会与云层中心比冰丸小得多的冰晶相撞。云层中心的温度大约在零下15摄氏度或者更低。在此温度下，冰丸和冰晶的撞击会使电荷发生转移，冰丸由此获得了负电而冰晶获得了正电。随后上升气流会将较轻的正电冰晶带到云的顶部。较重的负电冰丸会留在云层中部并积累起来。这个过程解释了为什么云的顶部带正电而中部带负电。带负电的区域非常大：厚度达数百米，直径达几千米。位于这片又大又冷的带负电区域之下的云层的温度要高于零下15摄氏度，在此温度下，冰晶和降落的冰丸的碰撞会产生带正电荷的冰丸，于是在云层的底部聚集成一小片区域。
5.According to paragraph 2. why are positively charged ice pellets produced in the lower part of the cloud?
A. Collisions between ice crystals and ice pellets increase 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. Temperatures in the lower part of the cloud are warmer than -15°C.
解析：以positively charged ice pellets做关键词定位至最后一句，说在这个很大的，带负电的区域之下，碰撞产生了positively charged pellets，所以答案是D。A的increase in number，B的smaller和C的比较原文都没说
【2】形成雷雨云的带电粒子的分离具有一种三明治结构。带正电的粒子聚集在云的顶部和底部，但是中间区域形成的是带负电的粒子。近期的野外测量以及实验室模拟为这种带电粒子的排列结构提供了可能的解释。实际上在此过程中在云层较冷的上部区域形成了细小的(毫米到厘米大小)冰丸。当这些冰丸飘落时，一部分会与云层中心比冰丸小得多的冰晶相撞。云层中心的温度大约在零下15摄氏度或者更低。在此温度下，冰丸和冰晶的撞击会使电荷发生转移，冰丸由此获得了负电而冰晶获得了正电。随后上升气流会将较轻的正电冰晶带到云的顶部。较重的负电冰丸会留在云层中部并积累起来。这个过程解释了为什么云的顶部带正电而中部带负电。带负电的区域非常大：厚度达数百米，直径达几千米。位于这片又大又冷的带负电区域之下的云层的温度要高于零下15摄氏度，在此温度下，冰晶和降落的冰丸的碰撞会产生带正电荷的冰丸，于是在云层的底部聚集成一小片区域。
paragraph 5.
The formation of the channel is initiated when electrons surge from the cloud base toward the ground. When a stream of these 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 arises from a tall pointed structure such as a metal flagpole or a tower. That is why the subsequent lightning that follows the completed channel often strikes a tall structure. █
9. According to paragraph 5. which of the following is true of the stream of charged particles from the ground?
It prevents streams of electrons from the cloud from striking the ground
It completes a channel that connects the storm cloud with the ground
It produces a stream of electrons from the cloud
It widens the path made by the initial stream of electrons from the cloud
解析：以stream of charged particles from the ground做关键词定位至第二句，说来自地面的带负电的电子流会在地面以上100米左右碰上来自云层的带正电的电子流，然后又说当二者碰在一起的时候就形成了通路，所以B形成通路是正确的。A的prevent，C的produce和D的widen原文都没说
【5】电子从云层基部涌向地面就会开始形成通道。当这些负电荷距离地面不到100米的时候，会遇到来自地面的带正电的粒子流。一旦正负带电粒子流相遇，一条连接云层和地面的完整的通道便形成了。这个通道直径仅有几厘米，但是已经足以使电子以一道闪电这种可见的形式通过通道到达地面。那些与从云层涌来的电子相遇的带正电的粒子流通常来自于高大的带尖顶的建筑物，例如金属旗杆或塔。这就是为什么接下来通过完整通道的闪电往往会击中高层建筑的原因。
以上就是托福阅读TPO18-3中的事实信息题及其解析，大家可以在备考的时候参考复习，希望能够帮助大家的考前准备。最后前程百利祝大家都能取得理想的托福考试成绩。
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