substitution

名词 substitution:

1. an event in which one thing is substituted for another
   同义词：permutation, transposition, replacement, switch
2. the act of putting one thing or person in the place of another: "he sent Smith in for Jones but the substitution came too late to help"
   同义词：exchange, commutation

1. Two substitutions (ie of players) were made during the match.
   在比赛中换了两次人。