【单选题】听力原文: William Shakespeare was christened in the market town of Stratford on Avon, Warwickshire, on April 26,1564; traditionally, his actual birthday was three days earlier, on St. George's day, the sa...
【简答题】元素周期表是学习和研究化学的重要工具.下表是1-3周期元素的部分信息: 1 H 1.008 2 He 4.003 3 Li 6.974 4 Be 9.012 5 B 10.81 x C 12.01 7 N 14.01 8 O 16.00 9 F 19.00 10 Ne 20.18 11 Na 22.99 12 Mg 24.31 13 Al 26.98 y Si 28.09 15 p 30.97 1...