Question

阅读理解

阅读下列短文，从各题所给的A、B、C、D四个选项中，选出最佳选项。

　　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 past 15 years, pilots have reported well over 100 incidents that have been caused by electromagnetic interference (电磁干扰). The source of this interference remains unconfirmed, but increasingly, experts point the blame at portable computers, radios 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 - oft and landing. Some experts have gone further, calling for a total ban during the flight. Currently, rules on using these devices are left up to individual airlines. And although some airlines forbid passengers from using such equipment during take - off and landing, most are reluctant (勉强) to enforce a total ban, given that many passengers want to work during the flight.

　　The difficulty is predicating how electromagnetic fields might affect an aircraft's computers. Experts know that portable devices give out radiation, which affects wave lengths 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 (易受损的) to interference raises the risk that terrorists may use a radio system in order to damage navigation equipment.

1．The passage above mainly talks about ________.

[　　]

A．a new rule for airlines

B．the disadvantages of electronic devices

C．a possible cause of aircraft crashes

D．safety measures for air flight

2．Over 100 air- crash incidents have taken place during the past fifteen years, the reason is probably that ________.

[　　]

A．they may have been caused by the damage to the radio system

B．they may have taken place during the take - off and landing

C．they were proved to have been caused by the passengers' portable computers

D．the pilots are not expert at electromagnetics

3．Few airlines wish to entirely forbid passengers to use electric devices because ________.

[　　]

A．they don't believe in such a danger as radio interference

B．the harmful effect of them is yet to be proved

C．most passengers don't want to take a plane which doesn't allow the use of radios or cassette players

D．they will take other safety measures

4．It can be inferred from the passage that the writer ________.

[　　]

A．is in favor of forbidding passenger's use of electronic devices completely

B．hasn't formed his own opinion on the problem

C．regards it as unreasonable to forbid using electric devices during the flight completely

D．strongly believe that air incidents are caused by electromagnetic interference

Answer 1

答案：C;A;B;A