substitution

例句：

1. 1. The doctor substituteda new heart valve for the old one.
   医生用一个新的心脏瓣膜替换了旧的。
2. 2. She substituted her own ideaswith her husband's suggestions.
   她用自己的想法取代了丈夫的建议。
3. 3. Thecompany decided to substitute itsemployees with robots.
   公司决定用机器人来替换员工。