题目内容：
根据下列文章,请回答题。Solar StormAt the end of October 2003, A sudden solar storm hit the earth. A solar storm refers to the large a mounts 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 coron A( 日冠) on October 28, 2003. Large a mounts of charged particles moved 150,000,000 kilometers through space toward the __________ (55) in 19 hours. They could a ffect aircra ft roa ming (漫游) in space.
The high-energy particles will __________ (56) some of the parts of an aircra ft. They may also cause it to fail. High-energy particles can threaten the sa fety of an aircra ft at A high orbit. If an aircra ft orbits at Alower orbit, it is __________ (57) because it is under the protection of the earth's ma gnetic field.
A solar storm not only a ffects aircra ft but also is a __________ (58) to the environment and humans. The a erosphere and ma gnetic field of the earth can __________ (59) humans from ultra violet radiation and X-rays. While most of the X-rays are absorbed a fter they enter the a erosphere (大气层), still A few can __________ (60) the ground.
The geoma gnetic storm caused by this round of solar storm reaches its highest level on the two __________ (61) of the earth, which a ffects 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 suchA solarstorm, it __________ (63) we receive ten times the X-ray radiation. It's really da ma ging.
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. A．since
B．when
C．until
D．though
参考答案：
答案解析：