樓上的句子到處都是語(yǔ)法錯(cuò)誤.要改你的句子都要寫(xiě)一大篇了.干脆只告訴你正確的句子吧：
It was Lily who came up with the idea that people should drink more soft drink.
這里,idea和that people should drink more soft drink是等同的,所以that people should drink more soft drink是個(gè)同位語(yǔ)從句.注意idea不是樓上所說(shuō)的主語(yǔ).這句話(huà)的主語(yǔ)是It.
略微把上句改一下,就可以造出一個(gè)主語(yǔ)的同位語(yǔ)來(lái)：
Lily, the girl who came up with the idea that people should drink more soft drink, is in my class.
這樣,the girl就是Lily的同位語(yǔ).后面的who came up with the idea是定語(yǔ)從句.而that people should drink more soft drink仍然是idea的同位語(yǔ).
記住同位語(yǔ)和它所修飾的詞是完全等價(jià)的.再給你一些例子：
My sister Helen will come with us.
Helen是同位語(yǔ),修飾my sister.
The news that he died shocked everyone.
that he died是同位語(yǔ)從句,修飾the news.