不才有一個小問題是有關於關係代名詞(做介係詞受詞時)所引導的形容詞子句.

That is the house in which we live. (Which做形容詞子句中介係詞in的受詞)

先行詞為house,形容詞子句關代拿掉是 "we live in the house" 這邊意思很明確,可是下一句就很怪..

原文為:Ma Huang has also been shown to increase the rate at which fat is burned(Which做介係詞at的受詞),是說增加脂肪燃燒的速率.

先行詞為rate,形容詞子句關代掉拿掉後是 fat is burned at rate 這啥意思?
這句看了一下午腦中是一片混亂,望高人出手解答...

感激不盡....