【答案解析】The first sentence should be differentiated from the other these sentences since the first one is unclear in meaning while the others are clear in meaning. In the first sentence, the word "他" is ambiguous in that it is unable to identify whether it refers to lao wang or lao zhang. Therefore, it is unclear whether lao wang looked for his son or zhang"s son. The remaining sentences all showed that the person lao wang looked for is his own son, not zhang"s son.
From this group of sentences, some features of the Chinese language could be figured out: first, the Chinese reflexive "自己" and complex reflexive "他自己" are subject-oriented, that is, they are co-referential to the subject. Second, the reflexive "自己" can be displaced when it functions as the attribute modifier. Third, the non-reflexive pronoun "他" is not bound to the subject.