18. Modern navigation systems, which are
found in most of today’s commercial aircraft, are made with low-power
circuitry, which is more susceptible to interference than the vacuum-tube
circuitry found in older planes. During landing, navigation systems receive
radio signals from the airport to guide the plane to the runway. Recently, one
plane with low-power circuitry veered off course during landing, its dials
dimming, when a passenger turned on a laptop computer. Clearly, modern aircraft
navigation systems are being put at risk by the electronic devices that
passengers carry on board, such as cassette players and laptop computers.
Which one of the following, if true, LEAST
strengthens the argument above?
(A) After the laptop computer was turned
off, the plane regained course and its navigation instruments and dials
returned to normal.
(B) When in use all electronic devices emit
electromagnetic radiation, which is known to interfere with circuitry.
(C) No problems with navigational equipment
or instrument dials have been reported on flights with no passenger-owned
electronic devices on board.
(D) Significant electromagnetic radiation
from portable electronic devices can travel up to eight meters, and some
passenger seats on modern aircraft are located within four meters of the
navigation systems.
(E) Planes were first equipped with
low-power circuitry at about the same time portable electronic devices became
popular.
为什么选E不选A？？
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