The new members of the class received supplementary instruction.班级的新成员补了课。 There is a supplementary water supply in case the rain supply fails.万一主水源断了，我们另外有供水的地方。
用作表语
▲ S+be+～+prep.-phrase
In this plant oil is supplementary to coal as fuel.在这个工厂，油是煤的补充燃料。