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  3. The biggest safety threat facing today may not be a terrorist with a gun, but the man with the portable computer in business cla

The biggest safety threat facing today may not be a terrorist with a gun, but the man with the portable computer in business cla

admin2011-03-26  108
问题     The biggest safety threat facing today may not be a terrorist with a gun, but the man with the portable computer in business class. In the last 15 years, pilots have reported well over 100 incidents that could have been caused by electromagnetic interference. The source of this interference remains unconfirmed, but increasingly, experts are pointing the blame at portable electronic devices such as portable computers, radio and cassette players and mobile telephones.
    RTCA, an organization which advises the aviation (航空) industry, has recommended that all airlines ban (禁止) such devices from being used during "critical" stages of flight particularly take- off and landing. Some experts have gone further, calling for a total ban during all flights. (76) Currently, rules on using these devices are left up to individual airlines. And although some airlines prohibit passengers from using such equipment during take-off and landing, most are reluctant to enforce a total ban, given that many passengers want to work during flights.
    The difficulty is predicting how electromagnetic fields might affect all aircraft’s computers. (77) Experts know that portable devices emit radiation which affects those wavelengths which aircraft use for navigation and communication. But, because they have not been able to reproduce these effects in a laboratory, they have no way of knowing whether the interference might be dangerous or not.
    The fact that aircraft may be vulnerable (易受捐的) to interference raises the risk that terrorists may use radio systems in order to damage navigation equipment. (78) As worrying, though, is the passenger who can’t hear the instructions to turn off his radio because the music’s too loud.
The reason why few airlines want to impose a total ban on their passengers using electronic devices is ______.
选项 A、they don’t believe there is such a danger as radio interference
B、the harmful effect of electromagnetic interference is yet to be proved
C、they have other effective safety measures to fall back on
D、most passengers refuse to take a plane which bans the use of radio and cassette players
答案B
解析 本题问：这一题考核的是对文章全篇内容的正确理解。航空安全问题涉及乘客的生命，如若事实证明使用这种设备是导致空难的原因，那么各航空公司全程禁止使用这种设备是不会遭到乘客的拒绝的，但正是这一点尚未得到证实，所以各航空公司对全程禁止使用这种设备尚犹豫不决。因此本题的答案是B项。
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