目的状语的逻辑主语是句子的主语；宾语补足语的逻辑主语是句子的宾语.
例如：I have bought this notebook to write my diary.
I-主语,have bought-谓语,this notebook-宾语,to write my diary-目的状语（逻辑主语是I)
He asked me to write a letter.
He-主语,asked-谓语,me-宾语,to write a letter-宾语补足语（逻辑主语是me)
目的状语和宾补得区别由不定式构成的目的状语一般跟在宾语后面的,和宾补有什么区别啊,总是弄混,