The reincarnated leaders were always “discovered” in the households of lowly families 20 noble ones.
答案：(B) rather than
依照文意（發現的繼承者總是出身卑微家庭，而不是貴族家庭），加上下一句「這是為了確保沒有強大的貴族家庭能奪取頭銜」的因果印證，語意上是對比「而不是貴族家庭」，rather than（而不是）符合這個邏輯；as a result of（由於……的緣故）會讓因果關係變得不通順。
四個選項都是好幾個字組成的一組，長得都很像那種幾個字合起來當一個介系詞用的說法（劍橋 English Grammar Today 的 Prepositions 條目），於是你很容易一個一個代進去唸唸看哪個順，唸到 as a result of 覺得「因為貴族家庭」好像也講得通，就停在那裡。答對率只有五成出頭，多半是這樣丟掉的。其實這一格有一個看得見的訊號，不必靠語感。
四個選項都能直接接名詞，可見這一格考的不是文法而是「兩邊的語意關係」：是對比、排除，還是因果。訊號就在空格兩側——前面是 lowly families（出身低微的家庭），後面是 noble ones（顯貴的家庭），lowly 與 noble 是一組反義詞，而 ones 是代替 families 的替代詞（掛鉤是國中的 I have two pens. One is red; the other is blue.）。同一個名詞、相反的形容詞擺在空格兩邊，這一格要的就是「是前者，不是後者」，rather than（而不是）正是做這件事的。再用下一句驗算：This was to ensure that no single and powerful noble family could seize the title（這是為了確保沒有哪個有權有勢的貴族家庭能奪走這個頭銜），整段的用意就是把貴族排除在外，與 rather than 完全同向。這一題的鑑別度有 46，分開的就是有沒有看出 lowly 與 noble 這一組對立。
as a result of（由於……）：填進去會變成「因為貴族家庭而被發現在平民家庭裡」，因果講不通，下一句的用意還正好相反。relative to（相對於）：用在拿一個基準去衡量比例或程度（The house is cheap relative to our income. 相對於我們的收入，這房子算便宜。），不是二選一的排除。with regard to（關於）：用來帶出要談的主題（with regard to your question 關於你的問題），後面接的是話題，不是被排除的對象，本身完全沒有對比的意思。
A rather than B（是 A 而不是 B）、would rather V than V（寧願……而不願……）、rather than V-ing（而不是做……）、as a result of（由於……）、with regard to（關於）、relative to（相對於）。
Whenever a Dalai Lama died, a search began for his reincarnation. The 16 male child had to have certain qualities. 17 was the ability to identify the belongings of his predecessor, or rather his previous self. Another requirement was 18 he should have large ears, upward-slanting eyes and eyebrows. Besides, one of his hands should bear a mark like a conch-shell. The successful candidate, usually 19 two or three, was then removed from his family to Lhasa to begin spiritual training for his future role. The Panchen Lamas were chosen in a similar way.
The reincarnated leaders were always "discovered" in the households of lowly families 20 noble ones. This was to ensure that no single and powerful noble family could seize the title and pass it to the next generation.