Hints: 本期学习的字源：pent-=five五 U.S. Department of Defense javelin 1,500-meter 单词不需要大写，单词与例句或不同词条之间换行即可。 注解中详细介绍了单词的拆分与释义，是学习字源分析的重中之重！一定记得听写后来看注解！
pentangle pentagon The U.S. Department of Defense is housed in a building in the shape of a pentagon. pentathlon In the pentathlon, a contestant takes part in the long jump, the javelin throw, the 200-meter dash, the discus throw and the 1,500-meter run.
The U.S. Department of Defense is housed in a building in the shape of a pentagon. 美国国防部位于一栋五角形建筑中。 In the pentathlon, a contestant takes part in the long jump, the javelin throw, the 200-meter dash, the discus throw and the 1,500-meter run. 五项运动的参赛者要参加跳远、标枪、200米短跑、铁饼和1500米长跑。