As a physician who travels quite a lot, I spend a lot of time on planes listening for that dreaded “Is there a doctor on board” announcement. I’’ve been (71) ________ only once —— for a woman who had merely fainted. But the (72) ________ made me quite curious about how (73) ________ this kind of thing happens I wondered what I would do if (74) ________ with a real midair medical emergency-with out access (75) ________ a hospital staff and the usual emergency equipment. So 76 the New England Journal of Medicine last week (77) ________ a study about in-flight medical s. I read it (78) ________ interest. The study estimated that there are a(n) (79) ________ of 30 in-flight medical emergencies on U.S. flights every day. Most of them are not (80) ________;fainting and dizziness are the most frequent complaints. (81) ________ 13% of them ——roughly four a day —— are serious enough to (82) ________ a pilot to change course. The most common of the serious emergencies (83) ________ heart trouble. strokes, and difficulty breathing. Let’’s face it: plane rides are (84) ________.For starters, cabin pressures at high altitudes are set at roughly (85) ________ they would be if you lived at 5,000 to 8,000 feet above sea level. Most people can tolerate these pressures pretty (86) ________ ,but passengers with heart disease (87) ________ experience chest pains as result of the reduced amount of oxygen flowing through their blood. (88) ________ common in-flight problem is deep venous thrombosis——the so-called economy class syndrome (综合症).(89) ________ happens, don’’t panic. Things are getting better on the in-flight-emergency front. Thanks to more recent legislation, flights with at (90) ________ one attendant are starting to install emergency medical kits to treat heart attacks.

A．by
B．of
C．with
D．in