Passage 4
The biggest safety threat facing airlines 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, record players and mobile telephones.
RTCA, an organization which advises the aviation industry, has recommended that all airlines ban such devices from being used during the "critical" stages of flight,particularly take-off and landing. Some experts have gone further, calling for a total ban during all flights. 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 an aircraft‘s computers. Experts know that portable devices emit radiation which affects those wavelengths which aircrafts 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 inference might be dangerous or not.
The fact that aircrafts may be vulnerable to interference raises the risk that terrorists may use radio systems in order to damage navigation equipment. As worrying, though, is the passenger who can‘t hear the instructions to turn off his radio because the music‘s too loud.
The passage is mainly about _____.
根据第一段"The biggest safety threat facing airlines today may not be a terrorist with a gun, but the man with the portable computer in business class."并结合全文内容可知， 本文主要讲述的是移动电子设备的使用可能成为空难发生的一个原因。本题答案为C。
What is said about the 100 incidents in the past 15 years?
根据第一段最后"In the last 15 years, pilots have reported well over 100 incidents that could have been caused by electromagnetic interference."可知， 过去15年中， 这100起空难可能是由于电磁干扰引起的。 本题答案为D。
Few airlines want to impose a total ban on passengers using electromagnetic devices because _____.
根据第二及第三段内容， 虽然科学家已经证实了这些信号对飞机会产生影响， 但是却无法证明这些干扰是有害的。 所以有些航空公司不愿意让禁令全面生效， 因为它们的旅客需要在飞行途中工作。
Why is it difficult to predict the possible effects of electromagnetic fields on an airplane‘s computers?
根据第三段内容"But, because they have not been able to reproduce these effects in a laboratory, they have no way of knowing whether the inference might be dangerous or not."科学家们并不能在实验室里重新模拟出这种影响， 这就是他们无法证实电磁可能对飞机设备产生影响的原因所在。 本题答案为C。
It can be inferred from the passage that the author _____.
根据文章最后一段， 飞机易受电磁干扰加剧了恐怖分子使用无线电通讯干扰导航设备的可能性。 更糟糕的是， 乘客可能由于音乐声音太大而听不到要求关掉无线电设备的指示。 这反映了作者的担忧， 也表现了作者完全支持禁止乘客在飞机上使用无线电设备的措施。 本题答案为A。