The biggest safety threat facing airlines today may not be a terrorist with a gun, but the man with the --1-- computer in business class. In the last 15 years, pilots have reported well over 100 --2-- that could have been caused by electromagnetic interference. The source of this interference --3-- unconfirmed, but increasingly, experts are pointing the blame at portable electronic device 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 “ --4-- ” stages of flight, --5-- take-off and landing. Some experts , 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 --6-- to enforce a total ban, given that many passengers want to work during flights.

　　The difficulty is --7-- how electromagnetic fields might affect an aircraft’s computers. Experts know that portable device emit radiation which --8-- 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(易受损的)to interference raises the risk that terrorists may use radio systems in order to damage navigation --9-- . As worrying, though, who can’t hear the instructions to turn off his radio because the music’s too --10-- .

　　A) definite B) incidents C) effects D) remains

　　E) critical F) particularly G) reluctant H) refreshing

　　I) portable J) enormous K) predicting L) liberal

　　M) affects N) equipment O) loud

　　选词填空答案：1. I) 2. B) 3. D) 4. E) 5. F) 6. G) 7. K) 8. M) 9. N) 10. O)