填空题

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, (36) have reported well over 100 incidents that could have been (37) by electromagnetic (电磁的) interference. The source of this interference remains unconfirmed, but (38) , experts are pointing the blame at portable electronic (39) such as portable computers, radio and cassette players and (40) telephones. RTCA, an organization which advises the aviation industry, has (41) that all airlines ban such devices from being used during " (42) " stages of flight, particularly take-off and landing. Some experts have gone further, calling for a total ban during all flights. (43) , 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, (44) .
The difficulty is predicting how electromagnetic fields might affect an aircraft’s computers. Experts know that portable devices emit radiation which effects those wavelengths (波长) which aircraft use for navigation and communication. But, because (45) .
The fact that aircraft may be vulnerable to interference raises the risk that terrorists may use radio systems in order to damage navigation equipment. (46) .