The answer is: not very thoroughly, 27 they are executives, specialized experts, or ordinary people in the street.
答案：(C) whether
【句型】whether...or... 字詞搭配「不論是……還是……」，表示「不論他們是主管、專家、或一般人」；whoever（無論是誰，不太符合這個並列結構）、because（因為）、rather（而不是）都不合。
看到後面有 or，你可能想到 whether... or... 這組，但也可能因為 whoever 帶有「無論是誰」的味道，覺得它更貼「不論主管、專家還是路人」的語意。答對率只有 40%，whoever 就是主要的失分去處。這一題比的不是語意像不像，而是文法角色對不對。
用一個很乾淨的檢驗法：先數空格後面的子句缺不缺主詞。whoever 是複合關係代名詞，它自己必須在子句裡當主詞或受詞——Whoever comes first will get the prize.（誰先到誰得獎），whoever 就是 comes 的主詞。本題空格後面是 they are executives, specialized experts, or ordinary people in the street，主詞 they 已經在了，再放一個 whoever 進去就多出一個主詞，句子直接壞掉。whether 是連接詞，後面接完整子句，引導的是讓步：「不論是…還是…」，正好與句中的 or 呼應成 whether they are A, B, or C。語意也對得起來：前面說「答案是：並沒有很徹底」，接著要補一句「不管哪一種人都一樣」，正是讓步。再補一個常被混淆的點：whether 有兩種身分，一是引導名詞子句的「是否」（I don't know whether he will come.），二是本題這種讓步的「不論是…還是…」。看到 whether，先確認它引導的子句在整句裡扮演什麼角色，兩種用法就分得開。
whoever：本身要當子句的主詞，後面不能再出現 they。because（因為）：整句沒有在解釋原因，而且 because 沒辦法與後面的 or 串起三種身分。rather（相當地、寧可）：是副詞，不能引導子句；要表達「而不是」得用 rather than，而且 rather than 後面接的是對等的成分，不是一個完整子句。
whether A or B（不論是 A 還是 B）、whether or not（不論是否）、rather than（而不是）、would rather do（寧願做…）、specialize in（專攻、專門從事）、in the street（在街上）。
Most human beings actually decide before they think. When people encounter a complex issue and form an opinion, how thoroughly have they 26 all the important factors involved before they make their decisions? The answer is: not very thoroughly, 27 they are executives, specialized experts, or ordinary people in the street. Very few people, no matter how intelligent or experienced, can 28 all the possibilities or outcomes of a policy or a course of action within just a short period of time.
Those who take pride in being decisive often try their best to consider all the factors beforehand. 29 , it is not unusual for them to come up with a decision before they have the time to do so. And 30 an opinion is formed, most of their thinking then is simply trying to find support for it.