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问题 解答题

已知一个等腰三角形的周长为20cm。

（1）若其中一边长为6cm，求另外两边的长；

（2）若其中一边长为4cm，求另外两边的长。

答案

解：（1）分两种情况：

①当6cm为腰长时，设底边为x（cm），则 6×2+x=20，x=8，此时，另外两边分别为6cm，8cm。

②当6cm为底时，设腰长为y（cm），则 2y+6=20，y=7， 此时，另外两边为7cm，7cm。

（2）分两种情况：

①当4cm为腰长时，设底为x（cm），则4×2+x=20，x=12， ∵4+4<12，∴4，4，12不能组成三角形。 ②当4cm为底时，设腰长为y（cm），则 4+2y=20，y=8， 故此时另两边为8cm，8cm。

单项选择题

慢性阻塞性肺气肿的体征，下列哪一项是错误的（）

A.桶状胸

B.语颤增强

C.心音遥远

D.呼吸音减低、呼气延长

E.肝浊音界下移
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Education is compulsory and free for every child in the United States. Most children start school by the age of six. They attend eight years of (36) schools and four years of high school or (37) school. The money for free public schools comes from taxes, and each state is (38) for its own educational system. State legislatures set the educational requirements but leave the (39) of the schools in the hands of the (40) communities. Most states require their children to go to school until a certain age. This age (41) from 10 to 18 years according to the laws of the (42) states. The Federal government (43) funds to the states for additional school and school services.
(44) . One may go to a twoyear college, a four year college, a university, or a specialized professional school—either public or private. Most colleges admit students on the basis of their high school records. (45) . Many students receive scholarships from the schools, governments, or private foundations and organizations. (46) . Only 2 percent of the population of the country cannot read and write.
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