选出与其他两个单词不同类的一项。
( )(1)A. ruler B. fishC. hen
( )(2)A. thisB. thatC. is
( )(3)A. YesB. NoC. not
( )(4)A. activity book B. story bookC. pen
( )(5)A. cowB. horseC. animal
( )(6)A. cameraB. fanC. elephant
( )(7)A. boyB. girl C. fan
( )(8)A. it B. whoC. he