her enthusiasm fad at the thought of how long that might take,just to have her kids reject it
Her enthusiasm (fad at )[ the thought of ( how long that might take)] ,(just to have her kids reject it.)
主语: her enthusiasm
谓语: fad at
中括号是宾语。中间含一个从句。
最后的小括号是动词不定式,用作状语。
追问最后的状语修饰哪里啊