题目

30．在血液生化六项检查的化验单上，每种成分的正常值都有一个变化范围，对此，不正确的描述是( )。 A．内环境稳态不是恒定的，可在一定范围内波动 B．内环境稳态是一种相对稳定的状态 C．年龄、性别等个体差异会导致内环境的成分含量存在差异 D．该变化范围主要考虑了化验结果的误差 答案：DCFlags have existed for over 3000 years.The earliest flags were wooden or metal poles topped with a carving.About 2000 years ago pies of fabric were added to some poles for decoration.Over the next 500 years the free-flying part of the flag became more important.Every country today has its own flag.Many groups and organizations also have a flag which stands for,or symbolizes,the aims of the group.The flag depicts (描绘)a world map,centered on the north pole.The map is surrounded by an olive(橄榄)wreath(花环)symbolizing peace and co-operation.The flag is blue and white.8.Flags have been in existence for _________.A.500 years                     B.over 3000 yearsC.about 2000 years              D.between 500 and 2000 years9.A very old flag is likely to _________.A.be made of fabric             B.have a map on itC.have white shapes on it       D.be made of carved wood10.An olive wreath is used to represent _________.A.peace         B.purity        C.justice       D.equality