If he sold the stone, he thought, he 23 enough money for the rest of his life.
答案：(C) would have
第二型條件句（與現在事實相反的假設：If + 過去式..., 主詞 + would + 原形動詞），表示「如果他賣了這顆寶石，他將會有足夠的錢」；had（不合這個假設語氣）、had had（過去完成式，不符合第二型條件句）、would have had（是第三型條件句的形式，用於與過去事實相反的假設，但這裡條件句If he sold用簡單過去式屬於第二型，應搭配would have）都不合。
看到 would have，很多人反射性把它接成 would have ＋ 過去分詞，覺得後面應該再來一個過去分詞，於是改挑 would have had。這裡要看清楚一件事：would have enough money 的 have 不是完成式的助動詞，它就是動詞本身，意思是「擁有」，後面接的是名詞 enough money，不是過去分詞。
先看 if 子句：If he sold the stone 用的是過去式。過去式的 if 子句表示與現在事實相反的假設，主要子句就配 would ＋ 原形動詞。還原成白話驗算：他其實沒有把寶石賣掉，所以「他這輩子就衣食無缺了」只是想像中的結果——這是與現在事實相反，不是與過去事實相反。這個公式你國中就背過最短的版本：If I were you, I would tell him.（如果我是你，我會告訴他。）主要子句是 would ＋ 原形，本題的原形就是 have（擁有）。這一格鑑別度只有 31，偏低，連高分群考生也會失手，原因有兩個：一是 he thought 插在主詞與動詞中間，把句子切斷，讀的時候容易以為時態要再往過去推一層；二是 would have 這兩個字連在一起，長得太像 would have ＋ 過去分詞的前半截，對這個組合越敏感的人，反而越容易多想一步。110 年第 25 題與 114 年第 11 題考的都是 would have ＋ 過去分詞，可以拿來與本題對照：那兩題後面接的是貨真價實的過去分詞，本題接的是名詞。
had：把主要子句寫成單純的過去式，變成在敘述事實「他有足夠的錢」，但他還沒賣掉寶石，不合事實。had had：過去完成式，需要一個更早的過去參照點，句中沒有。would have had：這是與過去事實相反的假設，要配的 if 子句必須是 If he had sold the stone（過去完成式）；本題的 if 子句是 If he sold（過去式），兩邊搭不起來。判斷方法很單純：if 子句往前推一格，主要子句就跟著往前推一格，兩邊要對齊。
If ＋ 過去式, 主詞 ＋ would ＋ 原形動詞（與現在事實相反的假設）、If ＋ had ＋ 過去分詞, 主詞 ＋ would have ＋ 過去分詞（與過去事實相反的假設）、for the rest of one's life（一輩子、餘生）、have enough money（有足夠的錢）、sell something（賣掉某物）、come back to find somebody（回來找某人）。
A wise woman traveling in the mountains found a precious stone. The next day she met another traveler who was hungry. The wise woman generously opened her bag to 21 her food with the traveler. When the hungry traveler saw the precious stone, he asked her to give it to him. The woman did 22 without hesitation. The traveler left, rejoicing.
If he sold the stone, he thought, he 23 enough money for the rest of his life. But in a few days he came back to find the woman. When he found her, he said, "I know how valuable this stone is, but I'm giving it back to you, 24 that you can give me something even more precious. You gave me the stone without asking for anything 25 . Please teach me what you have in your heart that makes you so generous."