请做这题:We called Tom last night ,but there was not a______.(回答)请问,answer(答案)有复数形式存在吗?如果有请造个句子说明一下!We called Tom last night ,but there was not a______.(回答) 答案给的是awser ,且没有复数。哪里来的 reply?我是想问这里的答案为什么不用复数呢??>