还有,juice、soup、grass、ice,等这些词。我的目的是,弄懂诸如:a cake of soap,语法是正确的,那么 two cake of soaps是正确的,还是two cake of soap是正确的,为啥soap有复数? 如:a lump of sugar,语法是正确的,那么two lumps of sugars是正确的,还是two lumps of sugar是正确的,为啥sugar也有复数sugars? 到底这些不可数名词的复数形式,代表啥意思?谢谢。