substitution
n
1 [U] substituting or being substituted 代替; 替换; 代理; 取代.
2 [C] act of substituting 代替; 替换; 代理; 取代
Two substitutions (ie of players) were made during the match. 在比赛中换了两次人.
A burst of activity associated with the laying of submarine cables soon confirmed the Challenger's observation that many parts of the ocean were two to three miles deep,