【简答题】International governments' inaction concerning sustainable development is clearly worrying but the proactive ( 主动出击的 ) approaches of some leading-edge companies are encouraging. Toyota, Wal-Mart, DuPo...
【单选题】图( a )是演示简谐振动图象的装置。当盛沙漏斗下面的薄木板 N 被匀速地拉出时,摆动着的漏斗中漏出的沙在板上形成曲线,该曲线显示出摆的位移随时间变化的关系,板上的直线 OO 1 代表时间轴。图( b )表示两个摆中的沙在各自木板上形成的曲线,若板 N 1 和板 N 2 拉动的速度 v 1 和 v 2 的关系为 v 2 = 2v 1 ,则板 N 1 、 N 2 上曲线所代表的振动的周期 T 1 和...
【简答题】The pollution in our country is very serious, which is harmful to our health. If we don’t take to protect the environment, the earth will be destroyed. The earth is our home. No earth, no people! So ...