A recent study found that when rats were forced to swim—an activity that places them under stress for a short while—they remembered their way through mazes far 14 than rats that were in a relaxed state.
答案：(B) better
far + 比較級 + than 為強調比較級的固定搭配。better（good 的比較級）符合「記得比較好」的文意；harder 不能自然修飾 remember 的表現優劣，less 語意相反（記得較差），further 則不符合語境（與距離無關）。
四個選項都是比較級，後面又跟著 than，很容易直接認定這是比較級的文法題，開始檢查形態對不對。但四個形態都對，這一格真正在問的是：哪一個副詞跟 remember 這個動作搭得起來。
先把句子的主要結構拉出來：they remembered their way through mazes far ___ than rats that were in a relaxed state.（牠們記得走出迷宮的路，比處於放鬆狀態的老鼠……）空格修飾的是 remembered 這個動作，要回答的是「記得得怎麼樣」。空格前面那個 far 也值得順手認識：它是用來加強比較級的字之一，劍橋 English Grammar Today 的 Comparison: adjectives 條目列出可以強調比較級的有 much、a lot、far、even、rather。四個選項裡，能說明記得的程度、方向又與整段一致的只有 better——整段都在講短期壓力讓記憶更敏銳。
harder 講的是用力、費勁，remember hard 不是英文會有的說法；真要講努力回想，用的是 try hard to remember。less 方向相反，代進去變成記得比較差，與前一句 Small amounts of stress hormones may even sharpen our memory. 直接牴觸。further 是距離或程度上的「更遠、更進一步」，可以說 look further into the matter，但不拿來評價記憶的好壞。鑑別度只有 32，原因是這一格不考推理：答案落在 remember 與哪個副詞搭配，前後文再讀幾遍也推不出來，反而是對比較級規則越熟的人越容易在四個形態之間繞一圈，繞回原點。
remember sth better（記得更清楚）、much／a lot／far／even／rather ＋ 比較級（可以加強比較級的字）、sharpen one's memory（使記憶更敏銳）、find one's way through（找到穿過……的路）、place sb under stress（使某人承受壓力）、be in a relaxed state（處於放鬆的狀態）
We all know that too much stress is not good for our health, but too little is not ideal, either. While 11 stress can be dangerous to the body, short-term stress is actually healthy.
Short-term stress triggers the production of protective chemicals in our body and strengthens the body's defenses. 12 our body is in a vulnerable situation, a burst of stress will quickly mobilize the body's own repair system to defend the damaged areas. This 13 us from physical discomfort and sickness.
Small amounts of stress hormones may even sharpen our memory. A recent study found that when rats were forced to swim—an activity that places them under stress for a short while—they remembered their way through mazes far 14 than rats that were in a relaxed state.
The key to a healthy lifestyle is to keep our stress level 15 . Too much stress will make us cranky and sick. Too little stress, on the other hand, will lead to boredom and low motivation.