选出与其他两个单词不同类的一项。
( )(1)A. ruler B. fish C. hen
( )(2)A. this B. that C. is
( )(3)A. Yes B. No C. not
( )(4)A. activity book B. story book C. pen
( )(5)A. cow B. horse C. animal
( )(6)A. camera B. fan C. elephant
( )(7)A. boy B. girl C. fan
( )(8)A. it B. who C. he