she said she came from china and that she was eighteen.
said後面接有兩個賓語從句，第二個從句前面的that不可省。
妳說的是這個特殊用法嗎？
壹般來講動詞或短語後面接的賓語從句前面可以加that也可省略，沒什麽特別要求。如：
they found out(that)....
she thinks(that)...
但做同位語時that不可省略。如：
i don't know the fact that ....
they've got the news that ...
這裏that後面的句子表示news和fact的內容。