The osteopenia incidence rate of lumbar vertebrae of each agegrade is obviously higher than that of femoral neck (P < 0. 05 ). The incidence of the osteopenia increased with age increasing.
各年龄组腰椎低骨量发生率显著高于股骨颈（P〈0．05），两部位低骨量发生率均随年龄增加而逐渐增加。
2
3rd grade (age 8).
三年级(8岁)。
3
Brazil is among the world champions in grade repetition, with 30% more children in primary school than the total in the 7-14 age group.