现在分词完成式~
前面跟了它的逻辑主语the boy
现在分词的逻辑主语可以放在它前面,如果是名词,就要用所有格形式,代词的话,就用形容词性物主代词~
比如 His not coming
造个句子：We were suprised at his not passing the exam.