SSAT阅读真题一篇.

SSAT阅读真题一篇 Directions: Read each passage carully and then answer the questions about it. For each question, decide on the basis of the passage which one of the choices best answers the questions. Radiation from the Sun continuously breaks two-atom oxygen molecules into single atoms. Some of these link up with ordinary oxygen molecules and form ozone. Some rejoin other free singles and revert to stable molecules. This Sun-energy process, if lt undisturbed, maintains a fairly constant supply of ozone above the Earth’s surface. The ozone layer begins about eight miles up and is distributed thinly to about thirty miles up. This lofty umbrella of ozone shields the Earth from much of the Sun’s deadly ultraviolet rays. Without the ozone cover, life on Earth would be literally sunburned to death. Some scientists believe that relatively small amount of synthetic chemicals, such as spray-can fluorocarbon or jet exhaust, reach the upper limits of the atmosphere and break down the three-atom ozone molecules. It is also believed that just one atom of the spray-can or get pollutant can affect vast numbers of ozone molecules. Weather research satellites have observed the ozone shield in great detail, but their data have neither put to rest the “doomsday theories” nor incited a global campaign to stop destroying the Earth’s protective covering. 1. According to the passage, ozone is a (A) kind of radiation (B) deadly ultraviolet ray (C) combination of oxygen atoms (D) synthetic chemical (E) free-floating atom 2. The destruction of the ozone layer would most likely result in a decrease in (A) life on Earth (B) air pollution (C) spray-can gases (D) severe cases of sunburn (E) radiation from the Sun