1．substitute 用作不及物动词作“做代替者”解，是美国用法。例如：As Mr Sinclair was ill, Mr Cook substituted as our teacher of chemistry.

2．下面四句意思相同：
We have to substitute tea for coffee.
We have to substitute coffee by tea.
We have to substitute coffee with tea.
Tea has to substitute coffee.
第一句是正当的，其他三句都不算正当。substitute 的正确意思是“把……用作代替者”，不是“把某人或某物代替（某人或某物）”或“代替（某人或某物）”。下面每组里的三句都不该说：
第一组该改作 He omitted of and substituted for (for it)，第二组该改作 For was substituted for of.