These nets are recognized by medical experts as the best hope for 22 the spread of malaria－Cambodia's most deadly disease. 23 the Health Ministry and the Malaria Center, The CAMBODIA DAILY will distribute the nets to the most 24 areas of the country. 25 to this campaign and save three lives for only $5, send your donation to: American Assistance for Cambodia, P.O.
答案：(A) affected
affected 是「受影響的」，the most affected areas 指疫情最嚴重、受害最深的地區；frequent（頻繁的）、effective（有效的）、included（被包含的）語意都不合。
affect 與 effect 的意思不難分，難在拼字只差第一個字母，發音又極接近（affect /əˈfɛkt/、effect /ɪˈfɛkt/），字首都輕讀。
判斷的依據在空格前後兩側：前面是 the most、後面是名詞 areas，可知空格要填形容詞或作形容詞用的分詞。affected 是 affect 的過去分詞，作形容詞用是「受影響的」，the most affected areas 即「受害最深的地區」。作答線索在首句 The CAMBODIA DAILY is launching a world-wide campaign to wipe out malaria in Cambodia.（《柬埔寨日報》正發起一項全球性活動，致力於根除柬埔寨的瘧疾），全文談的是瘧疾防治，蚊帳自然優先發送到疫情最嚴重的地區。凡是空格前有 the most 的題目，判斷步驟相同：先確認空格後的詞性，再檢查各選項能否作形容詞用。
frequent 是「頻繁的」，用於形容事件發生的次數，不用來形容地區受害的程度。effective 是「有效的」，與 affected 僅一字母之差，意思卻是「產生效果的」，the most effective areas 語意不通。included 是「被包含的」，與全文語意不合。名詞 effect 與動詞 affect 的分辨方式是看位置：前面有冠詞或形容詞時用名詞 effect，作句子的動詞時用 affect。
the most affected areas（受害最深的地區）、be affected by（受…影響）、have an effect on（對…有影響）、side effects（副作用）、take effect（生效）。其中 have an effect on 這一組考過 5 個年度，83 年第 21 題 →、87 年第 33 題 →、99 課綱學測參考用試卷第 30 題 →、103 年第 25 題 →都出現過。
The CAMBODIA DAILY is launching a world-wide campaign to wipe out malaria in Cambodia. You can help save three lives for only $5 by supporting this effort. Each and every dollar you contribute will go 21 the purchase of family-sized insecticide-treated mosquito nets costing $5 each. These nets are recognized by medical experts as the best hope for 22 the spread of malaria－Cambodia's most deadly disease.
23 the Health Ministry and the Malaria Center, The CAMBODIA DAILY will distribute the nets to the most 24 areas of the country. 25 to this campaign and save three lives for only $5, send your donation to: American Assistance for Cambodia, P.O. Box 2716, GPO, New York, NY 10116. Credit Card donations are also accepted.