1. 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。

① A. good         B. cook         C. moon

② A. forty         B. doctor        C.morning

③ A. brown        B.how          C. window

④ A. duty          B. bus           C. must

⑤ A. horse          B. house         C. mouse