单选题 Nerve signals may travel through nerve or muscle fibers at speeds as high as two hundred miles per hour.
  • A. velocities
  • B. impulses
  • C. ratios
  • D. atrocities


【正确答案】 A
【答案解析】[解析] speed：速度，与velocity(速度、快速)的意思相近；impulse：冲动；ratio：比、比率；atrocity：暴行。