Research on how chemicals in blueberries affect brain function even suggests that these chemicals may help our own brains work more 20.
答案：(C) efficiently
work more efficiently（運作更有效率）表示這些化學物質能幫助大腦運作得更有效率，呼應全文「吃得健康也能讓人更聰明」的主題；obviously／diligently／superficially 均不符合此處語意。
四個選項都是 -ly 結尾的副詞，形態一樣，你會憑中文哪個順挑一個。
鑑別度高達 57。四個選項都是副詞、都放得進 more 後面，形態這條路斷掉，考的是語意與搭配。空格前是 brains work more ______，先問「大腦運作得更怎麼樣才算是好事」——答案是更有效率，而 work efficiently（有效率地運作）正是成組的說法。填進去讀成 help our own brains work more efficiently（幫助我們的大腦運作得更有效率）。末句 eating richly colored fruits and vegetables makes us both healthier and smarter（吃顏色濃豔的蔬果讓我們更健康也更聰明）正是在替這一句收尾，可以拿來驗算。
obviously（顯然地）是說話者對事情明不明顯的評價，不是運作的方式；diligently（勤奮地）只用在人身上，大腦不會勤奮；superficially（表面地、膚淺地）是負面的，與整段的方向相反。三個都是 -ly 副詞，形態吻合，容易被順手選走。
work efficiently（有效率地運作）、brain function（大腦功能）、affect（影響）、in other words（換句話說）、superficially（表面地、膚淺地）、diligently（勤奮地）。
The fruits and vegetables we eat often come in distinctive colors. The rich colors, 16, are not there only to attract attention. They perform another important function for the plants. Research shows that the substances 17 these colors actually protect plants from chemical damage.
The colors come mainly from chemicals known as antioxidants. Plants make antioxidants to protect themselves from the sun's ultraviolet (UV) light, 18 may cause harmful elements to form within the plant cells.
When we eat colorful fruits and vegetables, the coloring chemicals protect us, too. Typically, an intensely colored plant has 19 of these protective chemicals than a paler one does. Research on how chemicals in blueberries affect brain function even suggests that these chemicals may help our own brains work more 20. In other words, eating richly colored fruits and vegetables makes us both healthier and smarter.