Directions : There are 20 blanks in the following passage. For each blank there are four choices marked A, B, C and D. You should choose the ONE that best fits into the passage. Then mark the corresponding letter on Answer Sheet with a single line through the centre. 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 1 only once – for a woman who had merely fainted. But the 2 made me quite curious about how 3 this kind of thing happens I wondered what I would do if 4 with a real midair medical emergency-without access 5 a hospital staff and the usual emergency equipment. So 6 the New England Journal of Medicine last week 7 a study about in –flight medical events. I read it 8 interest. The study estimated that there are a(n) 9 of 30 in-flight medical emergencies on U.S. flights every day. Most of them are not 10 ; fainting and dizziness are the most frequent complaints. 11 13% of them –roughly four a day – are serious enough to 12 a pilot to change course. The most common of the serious emergencies 13 heart trouble,strokes, and difficulty breathing. Let’s face it: plane rides are 14 . For starters, cabin pressures at high altitudes are set at roughly 15 they would be if you lived at 5,000 to 8,000 feet above sea level. Most people can tolerate these pressures pretty 16 , but passengers with heart disease 17 experience chest pains as result of the reduced amount of oxygen flowing through their blood. 18 common in-flight problem is deep venous thrombosis – the so-called economy class syndrome ( 综合症 ). 19 happens, don’t panic. Things are getting better on the in-flight-emergency front. Thanks to more recent legislation, flights with at 20 one attendant are starting to install emergency medical kits to treat heart attacks.