Fierce national competition 20 water resources has prompted fears that water issues contain the seeds of violent conflict.
答案：(A) for
competition for 意為「對…的競逐」，for 帶出爭奪的標的：各國對水資源的激烈競逐引發衝突疑慮；with 用於競爭的對手（compete with sb），to、at 都不合。
答對率 36%。
competition 你認得，但它後面該接哪個介系詞常被忽略。關鍵在於分清楚「跟誰爭」與「爭什麼」：competition 「with」 sb ＝ 與某人競爭（對手）；competition 「for」 sth ＝ 為了爭奪某物（標的）。本句空格後面是 water resources（水資源），那是被爭奪的東西，不是對手，所以用 for。
compete with sb for sth ＝ 與某人爭奪某物：Several companies are competing for the contract.（好幾家公司在爭這紙合約）。「遇到介系詞題，先問空格後面那個名詞在句中扮演什麼角色。」
前一句說即使供水充足的地方也面臨污染威脅；本句說各國激烈競逐水資源、引發衝突疑慮；下一句說國際合作因此刻不容緩。三句層層推進，主題就是「水資源不夠、大家在搶」。
competition for（對…的競逐）、competition with（與…競爭）、compete for a prize（爭奪獎項）、the demand for（對…的需求）。
More than 2.7 billion people will face severe shortages of fresh water by 2025. There is, 16, only a limited amount of water on the planet. Less than 3 percent of the world's water is fresh, and most of 17 is trapped in polar ice or buried underground in springs too deep to reach. Freshwater lakes, rivers and reservoirs may seem 18 but provide just a drop in the bucket.
Even 19 supplies are sufficient or plentiful, they are increasingly at risk due to various forms of pollution.
Fierce national competition 20 water resources has prompted fears that water issues contain the seeds of violent conflict. International cooperation is therefore by all means urgent.