题目

如图，在△ABC 中，D、E、F 分别是 BC、AC、AB 边的中点，AH⊥BC 于 H，HE=8，则线段DF的长是____________ 答案：【答案】8【解析】利用DF是△ABC的中位线，得到DF=EC，再利用Rt△AHC中，HE=AE=CE，推导得到DF=HE.∵点F、D分别时AB、BC的中点∴FD是△ABC的中位线∵点E是AC的中点，∴FD=AE=EC∵△AHC是直角三角形，点E是AC的中点∴HE=AE=EC∴DF=HE=8故答案为：8After lunch,I walked back home. I was just to cross the street when I heard the sound of a coin dropping. It wasn’t much but,as I turned, my eyes caught the heads of several other people turning too. A woman had dropped what appeared to be a dime.The tinkling sound of a coin dropping on pavement is an attention-getter．It Can be nothing more than a penny．Whatever the coin is，no one ignores the sound of it．It got me thinking about sounds again．We are surrounded by so many sounds that attract the most attention．People in New York City seldom turn to look when a fire engine，a police car or an ambulance comes screaming along the street．When I’m in New York，I’m a New Yorker．I don’t turn either．Like the natives，I hardly hear a siren(警报)there．However，at home in my little town in Connecticut，it’s different．The distant sound of a police car, all emergency vehicle or a fire siren brings me to my feet if I’m seated and brings me to the window if I’m in bed．It’s the quietest sounds that have most effect on us．not the loudest．In the middle of the night, I can hear a dripping tap a hundred yards away thigh three closed doors．I’ve been hearing little creaking noises and sounds which my imaginnation turns into footsteps in the middle of the night for twenty-five years in our house．How come I never hear those sounds in the daytime?I’m quite clear in my mind what the good sounds are and what the bad sounds are,I’ve turned against whistling，for instance：I used to think of it as the mark of a happy worker but lately I’ve been associating the whistler with a nervous person making unconscious noises．The tapping，tapping，tapping of my typewriter as the keys hit the paper is a lovely sound to me．I often like the sound of what I write better than the looks of it．小题1:The sound of a coin dropping makes people________A．think of moneyB．look at each otherC．pay attention to itD．stop crossing the street小题2:The author dislikes whistling because__________A．he has got tired of itB．it reminds him of tense peopleC．he used to be happierD．he doesn’t like workers小题3:What kind of sound does the author find pleasant?A．Tapping sound of his typewriter．B．Clinking sound of keysC．Tinkling sound of a coin dropping．D．Creaking sound of footsteps小题4:How does the author feel about sounds in general?A．They make him feel al home．B．He thinks they should be ignoredC．He prefers silence to loud noises．D．He believes they are part of our life