Is Mary the third one ----- the left? No,the first ------ th

Is Mary the third one _____ the left? No,the first ______ the right . A.from to B.from on C.on to这题还有个答案D.in from看答案里是选B 可是为啥捏?难道是因为第一个空前多了一个one 所以用from?没学过啊~~~~~~大虾们出手啊~~~速度快的补加分啊~~顺便再问一个：Here's a ______ bag.A.ten-kilos B.ten-kilo C.ten kilos D.ten kilo 选哪个。。。。。。