We must supersede old machines by new ones.我们必须以新机器取代旧机器。The use of robots will someday supersede manual labor.机器人的使用有一天会取代人力.We must supersede old machines by [ with ] new ones.我们必须以新机器取代旧机器....
化学家能把一种药物的各种成分分解出来.A chemist can separate a medicine into its components.化学家用电解法把水还原为氢.The chemist reduced water by electrolysis.了解这些稀有分子能帮助化学家找到可实现的目标。Understanding these rare molecules will help chemists to find out wh...