1974 IMO 第 1 题

I 1 (USA 4) ${ }^{\mathrm{IMO}}$ Alice, Betty, and Carol took the same series of examinations. There was one grade of $A$, one grade of $B$, and one grade of $C$ for each examination, where $A, B, C$ are different positive integers. The final test scores were | Alice | Betty | Carol | | :---: | :---: | :---: | | 20 | 10 | 9 | If Betty placed first in the arithmetic examination, who placed second in the spelling examination?

I 1 (USA 4) ${ }^{\mathrm{IMO}}$ Alice、Betty 和 Carol 参加了同一系列的考试。每次考试有一个等级$A$、一个等级$B$、一个等级$C$，其中$A、B、C$是不同的正整数。最终考试成绩为|爱丽丝|贝蒂 |卡罗尔 | | :---: | :---: | :---: | | 20 | 10 | 10 9 |如果贝蒂在算术考试中排名第一，谁在拼写考试中排名第二？