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)