找出画线部分读音与其他单词不同的选项，将序号填入括号内
(  )⑴A. good         B.cook          C.moon
(  )⑵A.forty         B.doctor         C.morning
(  )⑶A.brown         B.how           C.window
(  )⑷A.duty         B.bus           C.must
(  )⑸A.horse         B.house         C.mouse