Question

麻烦分析一下这个句子成分，详细的。谢谢

Unlike a professional athlete, which many believe he could have become, a ballet star never has the satisfaction of knowing a final score, or of beating the competition

Answer 1

先把整句翻译一下吧
许多人认为他本来会成为一名专业运动员，但他没有，不同于一名专业运动员，一名芭蕾明星从不会因为知道最后得分或打败一场比赛而获得成就感。
其实并没有一个词一个词的翻译，但大概就是这个意思了。
which 是指 a professional athlete, 而事实的结果，he肯定是一名芭蕾明星了。he could have become 后面应该是一个括号（a professional athlete），后面是将a ballet star 和athlete进行比较了，显然athlete是会因为知道比赛结果而成就感十足的。（题外话：大概是因为芭蕾舞选手关注的更多的是过程，那种酣畅淋漓的表演，而运动员追求的是成就的结果）
然后，最后就是satisfaction of 后面跟着两个宾语（knowing a final score和beating the competition）,后一个of 是可以省略的
over~~~~

Answer 2

Unlike a professional athlete,状语 which many believe he could have become（athlete的定语从句　　） {a ballet star 主语never has谓语 the satisfaction 宾语of knowing a final score, or of beating the competition补语}主句

Answer 3

依次是状语、定语从句、主谓宾