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.
答案：(C) One
前一句提到 certain qualities（複數），本句以 One 開頭列出第一項，下一句再以 Another requirement 接續，構成 One… Another… 的列舉呼應；It、All、This 都無法與下一句的 Another 形成這組對稱。
看到句首要填一個代名詞，你第一個想到的是 It（當形式主詞或指前句），或 This（指前面提過的事）。這兩個選項文法上都說得通，所以只看本句是選不出來的。
這一格要把前後三句連起來讀。前一句 The {16} male child had to have certain qualities.（這名男孩必須具備某些特質）——qualities 是複數；本句說其中一項是能認出前世自己的遺物；下一句 Another requirement was…（另一項條件是…）。One 與 Another 是英文列舉時固定的一組呼應，課本上就見過：To say is one thing; to do is another.（說是一回事，做是另一回事）。類似的句型：Of the two…, one…, the other…（兩者之中，一個…另一個…）；One…, another…, and still another…（一個…另一個…還有一個）；Some…, others…（有些…有些…）。遇到句首代名詞的空格，先往下掃一兩句，看到 another、the other、a second，前面那一格幾乎一定是 One。
It was the ability… 文法無誤，但 it 只是指稱，不帶「其中之一」的意思，與下一句的 Another 對不起來；All 語意錯誤——並不是所有特質都是「認出前世遺物」；This 指代前一句整體，同樣無法與 Another 對稱。
one … another …（一項…另一項…再一項）、for one thing…, for another…（一來…二來…）、some…, others…（有些…有些…）。其中 one … another … 這一組考過 3 個年度，89 年第 22 題 →、92 年第 24 題 →都出現過。
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.