The number of athletes 28 in the Summer Paralympic Games has increased from 400 athletes from 23 countries in 1960 to 3,806 athletes from 136 countries in 2004.
答案：(C) participating
現在分詞片語 participating in... 作後位修飾語，修飾前面的複數名詞 athletes，表示「參與帕運的運動員（人數）」；participate 是不及物動詞，運動員與「參與」這個動作是主動關係，所以用現在分詞修飾；to participate（不定詞）帶有尚未發生、未來要去做的語感，不適合描述本句這種已經發生、記錄在歷史統計數據裡的「參賽運動員人數」；participate（原形動詞）、participated（過去分詞被動）都不合。
讀到 The number of athletes ___ in the Summer Paralympic Games has increased...，你可能以為空格就是句子的主要動詞，於是在 participate 和 participated 之間猶豫，這一格只有五成一的人答對。真正的主要動詞在後面：has increased（人數增加了），主詞是 The number（數量）；空格填的是修飾 athletes 的後位修飾語。
先找主要動詞，再回頭看空格。句子已經有 has increased，如果空格再填一個限定動詞，整句就會出現兩個動詞卻沒有連接詞，所以空格只能是分詞或不定詞。接著判斷主動還是被動：還原成關係子句是 athletes who participate in the Games（參加帕運的運動員），運動員是自己去參加，屬於主動，所以用現在分詞 participating。國中學過的 a barking dog（＝ a dog that barks）正是同一個結構。
participate 是原形動詞，填進去會讓句子出現兩個主要動詞。participated 是過去分詞，過去分詞作後位修飾表示被動（a broken window ＝ a window that is broken），但 participate 是不及物動詞，本來就沒有被動式，這個選項在文法上就站不住。to participate 作後位修飾帶有「將要、有待去做」的意味，多半搭配序數或最高級（the first athlete to participate 第一位參賽的選手），與本句在報數字、講已經完成的歷史統計不合。
participate in（參加）、take part in（參加，與 participate in 同義）、the number of ＋ 複數名詞（……的數量）、a number of ＋ 複數名詞（許多……）、increase from A to B（從 A 增加到 B）、grow in size（規模擴大）
The Paralympics are Olympic-style games for athletes with a disability. They were organized for the first time in Rome in 1960. In Toronto in 1976, the idea of putting together different disability groups 26 sports competitions was born. Today, the Paralympics are sports events for athletes from six different disability groups. They emphasize the participants' athletic achievements 27 their physical disability.
The games have grown in size gradually. The number of athletes 28 in the Summer Paralympic Games has increased from 400 athletes from 23 countries in 1960 to 3,806 athletes from 136 countries in 2004.
The Paralympic Games have always been held in the same year as the Olympic Games. Since the Seoul 1988 Paralympic Games and the Albertville 1992 Winter Paralympic Games, they have also 29 in the same city as the Olympics. On June 19, 2001, an agreement was signed between the International Olympic Committee and the International Paralympics Committee to keep this 30 in the future. From the 2012 bid onwards, the city chosen to host the Olympic Games will also host the Paralympics.