选出不符合本组类别的单词。
1．_____________ shells, stamps, coins, since, dolls
2．_____________ going, skating, dancing, roller blading, skiing
3．_____________ marathon, contest, competition, computer, race
4．_____________ ago, since, when, months, books
5．_____________ beginner, lawyer, player, pro, champion
1．since 2．going 3．computer 4．books 5．pro
B
C
D
means______. 
B
C
D
