第6部分：完形填空（第51～65题，每题1分，共15分）
下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。
Solar Storm
At the end of October 2003， a sudden solar storm hit the earth. A.solar storm refers to the large amounts of charged particles released into space （51）the solar energy increases. The release of the energy （52） place along with the activity of the sunspots with a cycle of： 11 years. This time， the （53） of the storm exceeded expectations.
This （54） of intense solar storm was caused by the eruption of a solar flare （闪光） and the ejection （喷发） of the solar corona （日冠） on October 28， 2003. Large amounts of charged particles moved 150，000，000 kilometers through space toward the （55） in 19 hours. They could affect aircraft roaming （漫游） in space.
The high-energy particles will （56） 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 （57）because it is under the protection of the earth’s magnetic field.
A.solar storm not only affects aircraft but also is a （58） to the environment and humans. The aerosphere and magnetic field of the earth can （59） humans from ultraviolet radiation and X-rays. While most of the X-rays
are absorbed after they enter the aerosphere （大气层）， still a few can （60） the ground.
The geomagnetic storm caused by this round of solar storm reaches its highest level on the two （61） of the earth， which affects electricity supply of North America. Overexposure to （62） threatens the health of passengers on planes flying over the Polar Regions. If we fly in the sky during such a solar storm， it （63） we receive ten times the X-ray radiation. It’s really damaging.
Scientists say a solar eruption is like the sun sneezing， which will make the earth （64） a cold. Though this natural force is irresistible， scientists can still （65） its movement accurately by monitoring. Facing successive solar storms， humans can’t drop their guard
51 A.since B.when C.until D.though
52 A.finds B.adjusts C.holds D.takes
53 A.intensity B.height C.width D.density
54 A.piece B.part C.round D.set
55 A.star B.earth C.moon D.sun
56 A.dominate B.develop C.damage D.descend
57 A.safe B.dangerous C.comfortable D.manageable
58 A.limit B.cause C.force D.threat
59 A.separate B.benefit C.distinguish D.protect
60 A.lose B.reach C.break D.prepare
61 A.poles B.mountains C.rivers D.lakes
62 A.light B.storm C.radiation D.pressure
63 A.recommends B.means C.proposes D.advises
64 A.turn B.stop C.become D.catch
65 A.detect B.start C.experience D.change