his除了是形容词性物主代词以外，也可以是一个名词性物主代词，相当于his加上一个（或者多个）名词。例如，My car was bought three years ago. His was bought two years ago.在第二个句子中，his就相当于his car， 在句子中充当主语。那么把第二个句子变为一般疑问句，就是Was his bought two years ago?
his是一个形容词性物主代词，后边要跟名词。所以变一般疑问句需要看他后边跟的名词的单复数。如果是单数或者是不可数名词，一般疑问句用is开头，如果是复数用are开头
