完形填空
阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从4个选项中选择1个最佳答案。
Solar Storm
At the end of October 2003， a sudden solar storm hit the earth. A solar storm _1_ the large amounts of charged particles released into space when the solar energy increases. The release of the energy takes place _2_ with the activity of the sunspots with a cycle of 11 years. This time， the _3_ of the storm exceeded expectations.
This _4_ of intense solar storms was caused by the eruption of a solar flare and the ejection of the solar corona on October 28， 2004. Large amounts of charged particles moved 150，000，000 kilometers through space toward the _5_ in 19 hours. They could affect aircraft roaming in space. The high-energy particles will _6_ some of the parts of an aircraft. They may also cause it to fail. High-energy particles can threaten the safety of an aircraft at a high orbit. If an aircraft orbits at a lower orbit， it is safe because it is under the _7_ of the earths magnetic field.
A solar storm not only affects aircraft but also is a _8_ to the environment and humans. The aerosphere and magnetic field of the earth can protect humans from ultraviolet radiation and X-rays. _9_ most of the X-rays are absorbed after it enters the aerosphere， still a few can reach the ground. This kind of radiation， if any， only lasts for several minutes or dozens of minutes， so its effect on humans is very _10_.
The geomagnetic storm caused by this round of solar storm reaches its highest _11_ on the two poles of the earth， which affects electricity supply of the northern America. Overexposure to radiation threatens the health of passengers on planes flying _12_ the Polar Regions. If we fly in the sky during such a solar storm， it means we receive ten times the X-ray radiation. Its _13_ damaging.
Scientists say a solar eruption is like the sun sneezing， which will make the earth catch cold. Though this natural force is irresistible， scientists can _14_ detect its movement accurately by monitoring. Facing successive solar storms， humans cant drop their _15_.
1. A. refers to B. depends on C. prevents from D. acts on
2.A. among B. above C. along D. aboard
3.A. height B. intensity C. color D. shape
4.A. piece B. portion C. set D. round
5.A. sun B. earth C. star D. moon
6.A. delete B. determine C. damage D. detect
7.A. protection B. usage C. change D. float
8.A. resistance B. means C. help D. threat
9.A. Who B. While C. Where D. What
10.A. many B. much C. little D. few
11.A. position B. part C. concern D. level
12.A. with B. outside C. over D. on
13.A. really B. seldom C. hardly D. impossibly
14.A. too B. such C. so D. still
15.A. guide B. guard C. guess D. game
参考答案：ACBDB CADBC DCADB