His birthday is in October 为什么开头要用His

His birthday is in October 为什么开头要用His when is his birthday? 句子开头为什么不用what? his birthday is october tenth(用septeber fifth改为选择疑问句) His birthday is on October 15th.同义句 He ____ ____ on October His birthday is on october 5th.(对划线部分提问）划线的是His __________________?yes,his birthday is in december. His birthday is in November 同义句 His birthday is on . His birthday is( )July His birthday is His birthday is （）.A.on October ninth B.July ninth His birthday is-----------------january,中间是in还是on,