请教一道game 的题！ 谢谢

是黄皮书第二册第二套题Section1的第四道game。

题目的规则都没有看明白，做题自己乱猜， 错了2道，但是题目还是没明白…… 高人指点下吧！谢谢了！

Questions 19-24
　　Within a tennis league each of five teams occupies one of five positions, numbered 1 through 5 in order of rank, with number 1 as the highest position. The teams are initially in the order R, J, S, M, L, with R in position 1. Teams change positions only when a lower-positioned team defeats a higher-positioned team. The rules are as follows:　　

Matches are played alternately in odd-position rounds and in even-position rounds.　（就这句怎么也没明白）　

In an odd-position round, teams in position 3 and 5 play against teams positioned immediately above them.　　

In an even-position round, teams in position 2 and 4 play against teams positioned immediately above them.　　

When a lower-positioned team defeats a higher-positioned team, the two teams switch positions after the round is completed.

　　19. Which one of the of following could be the order of teams, from position 1 through position 5 respectively, after exactly one round of even-position matches if no odd-position round has yet been played?　　
　　(A) J , R, M, L, S　　
　　(B) J, R, S, L, M　　
　　(C) R, J, M, L, S　　
　　(D) R, J, M, S, L 　
　　(E) R, S, J, L, M

　　20. If exactly two rounds of matches have been played, beginning with an odd-position round, and if the lower-positioned teams have won every match in those two rounds, then each of the following must be true EXCEPT:　　
　　(A) L is one position higher than J.　　
　　(B) R is one position higher than L.　　
　　(C) S is one position higher than R.　　
　　(D) J is in position 4.　　
　　(E) M is in position 3.

　　21. Which one of the following could be true after exactly two rounds of matches have been played?　　
　　(A) J has won two matches.　
　　(B)L has lost two matches.　　
　　(C) R has won two matches.　
　　(D) L's only match was played against J.　　
　　(E) M played against S in two matches.

　　22. If after exactly three rounds of matches M is in position 4, and J and L have won all of their matches, then which one of the following can be true?　　
　　(A) J is in position 2.
　　(B) J is in position 3.　　
　　(C) L is in position 2.　　
　　(D) R is in position 1.
　　(D) S is in position 3.

　　23. If after exactly three rounds M has won three matches and the rankings of the other four teams relative to each other remain the same, then which one of the following must be in position 3?　　　
　　(A) J　　(B) L　　(C) M　　(D) R　　(E) S

　　24. If after exactly three rounds the teams, in order from first to fifth position, are R, J, L, S, and M, then which one of the following could be the order, from first to fifth position, of the teams after the second round?　　
　　(A) J, R, M, S, L　　
　　(B) J, L, S, M, R　
　　(C) R, J, S, L, M　　
　　(D) R, L, M, S, J　　
　　(E) R, M, L, S, J

指的是odd-position rounds and even-position rounds交替吧。就是一个odd-position rounds 下一个就是even-position rounds. 但是那个rounds第一并不确定。

是不是就是

一个odd-position rounds  一个 even-position rounds

我不太明白所谓odd-position rounds  是什么意思，

是指单数之间的比赛吗？但是这样解释好像做出来的答案不对。

而且不知道一个rounds一共有几场比赛啊？是所有的都要比一遍吗？

……唉，肯定是我太不关心体育比赛的结果……

u dont need to worry about this type of games

it is no longer in use

yeah

they decided not to design this type of games anymore