SAT 完全没想明白.
问题描述：
SAT 完全没想明白.
In a volleyball league with 4 teams,each team plays exactly 2 games with each of the other 3 teams in the league.What is the total number of games played in this league?
答
A,B,C,D 队,（3+2+1）*2=12 答案应该是12
A-B
A-C
A-D
B-C
B-D
C-D