题目

三．阅读理解：（20×2.5=50分） People have smoked cigarettes for a long time. The tobacco used to make cigarettes was grown in what is now part of the United States. Christopher Columbus, who discovered America, saw the Indians smoking, and soon the dried leaves were transported to Europe where smoking began to catch on. In the late 1800s, the Turk(土耳其人) made cigarettes even popular. Cigarettes smoke contains at least two harmful substances, tar and nicotine. Tar, which forms as the tobacco burns, damages the lungs and therefore affects breathing. Nicotine, which is found in 下列说法“①凡正方形都相似；②凡等腰三角形都相似；③凡等腰直角三角形都相似；④直角三角形斜边上的中线与斜边的比为1：2；⑤两个相似多边形的面积比为4：9，则周长的比为16：81．”中，正确的个数有（　　）个A．1B．2C．3D．4