参考答案

正确答案：A
解析：speed：速度。与velocity(速度；快速)的意思相近。Scientists spent years studying the velocity of light. 科学家们花了许多年研究光速。impulse：冲动。On impulse, I went into the shop and bought this expensive watch. 在一时冲动下，我走进商店，买下了这块昂贵的手表。ratio：比，比率。The ratio of pupils to teachers is 30 to 1. 学生与教师之间的比例是30比1。atrocity：暴行。They were guilty of the most barbarous and inhuman atrocities. 他们犯有最野蛮、最不人道的暴行。