题目

— You’ve worked there for half a year. What do you think about your boss? — He is a person who would try his best to ________ his purpose. A. accomplish        B. settle   C. perform                 D. undertake 答案：A 解析: 略 在H＝20 m高的阳台上，弹簧枪将质量为m＝15 g的弹丸以v0＝10 m/s的速度水平射出，弹丸落入沙坑后，在沙坑中运动的竖直距离h＝20 cm．不计空气阻力，试求： (1)弹簧枪对弹丸所做的功； (2)弹丸落到沙坑时的动能； (3)弹丸克服沙坑阻力所做的功．(g取10 m/s2)