mindfree!一个到现在都不懂得问题

大傻猫

2.although the ratio of physicians to total population is about the same in the us and canada, the us has 33% more surgeons per capita. clearly , this is the reason people in the us undergo 40% more operations per capita than do canadians.
答案是a: patients in the us do not have a greater need for surgery than do patients in canada.
我搞不明白那四个词的关系，physician,surgeon,operation,surgeon.
晴天猪说：physicians=surgeons
operation=surgery
可我还不明白

大傻猫

我现在理解通了，不过不知道对不对：
physician 不等于 surgeon, physician 做operation;
surgeon 专门做surgery的，但是也可以 do operation.
条件：两国physician人均人数一样，surgeon人均人数米国多33%;
只有假设了米国人均surgeon数小于加拿大的, 才能有多出来的surgeon来做operation。
mind free 这样解释对么？