Probability is the science of 30. It is among the fastest growing and most useful parts of today's mathematics.
答案：(B) chance
the science of chance（機率的科學）指機率學研究的正是「或然性／機率」，呼應前文討論的猜測與可能性；sport／future／weather 均不符合機率學的定義語境。
本題大考中心未公布逐題答對率，以下不談數據，只談觀念。
sport 與 weather 兩個選項都眼熟——這一篇從頭到尾在講美式足球、籃球和下雨，掃到選項時很容易覺得「剛剛看過」；future 也一樣，前面才出現過 how things will turn out in the future。但眼熟不等於正確，刻意從文章裡取用出現過的字來當誘答選項是常見的命題手法。
定案的依據就在前一句：The branch of mathematics that helps make our guesses more accurate is called probability.（這門幫助我們把猜測變得更準確的數學分支叫做機率。）既然上一句剛把這門學問命名為 probability，這一句 Probability is the science of ___ 就是在替它下定義，空格要填的是 probability 這門學問到底在研究什麼，也就是或然性、可能性——chance。這一篇還有一條值得注意的線：chance 在同一篇裡出現了三次，意思一路從具體滑向抽象。第一次是 a good chance of rain（很有可能下雨），講的是一件事的可能性；第二次是 the chances of overcoming that kind of lead are slim（扭轉那種領先差距的機會很渺茫），講的是勝算；第三次就是本題的 the science of chance，抽象成一整門學問要探討的東西。同一個字在一篇文章裡反覆出現時，回頭把前面幾次看一遍，往往就推得出這一次是什麼意思。
sport（運動）：文章拿球賽當例子，但機率不是研究運動的科學；weather（天氣）：下雨只是第一個例子，同樣不是這門學問的定義；future（未來）：前面確實提過未來，但機率研究的不是「未來」這個時間，是事情發生的可能性，兩者差一層。三個選項都是靠眼熟取勝，沒有一個接得上前一句的 probability。
the science of chance（研究或然性的科學）、probability（機率、或然性）、by chance（偶然、碰巧）、a branch of ＋ 學科（……的一個分支）、accurate（精準的）、among the fastest growing（成長最快的……之一）
Which would you wear to a football game, a sweater or a raincoat? 26 the raincoat if you thought there was a good chance of rain. Which basketball team is more likely to win, one that is 30 points ahead at the half or its opponent? Teams have been known to come from 27 to win, but the chances of overcoming that kind of lead are slim.
28 of us can be perfectly sure about how things will turn out in the future. But we can, and often do, think of the possibilities. We can try to guess 29 this or that might happen.
In some cases mathematics can help make these guesses more accurate. The branch of mathematics that helps make our guesses more accurate is called probability. Probability is the science of 30. It is among the fastest growing and most useful parts of today's mathematics.