The team has also developed a special device which uses scent bottles and visual trickery to make the wearers of these glasses think that the plain snack they are eating is 29 than it actually is.
答案：(D) tastier
語意「讓配戴者以為他們吃的平淡零食比實際上『更美味』」，tastier（更美味）呼應前文提到的氣味瓶跟視覺詭計讓人誤以為食物更好吃；prettier（更漂亮，這裡講的是味覺不是外觀）、larger（更大）、healthier（更健康）都不合。
前面整段都在講「食物看起來變大」，所以很容易順著選 larger。但這一句換了裝置，也換了感官，線索在這個句子裡面，不在前一段。
先看這個新裝置用什麼：scent bottles（氣味瓶）和 visual trickery（視覺把戲）。scent 是氣味，氣味影響的是味覺感受，所以被騙的內容應該和「好不好吃」有關。再看被形容的東西：the plain snack（平淡無味的零食）——plain 在這裡不是「樸素」而是「沒調味、味道平淡」，這個字已經先把主題定在味道上。一個沒味道的零食被騙成「比實際上更……」，最順的就是 tastier（更美味）。後文回頭確認了這一點：some participants thought that they were eating a chocolate snack, but in fact they were not（有些受試者以為自己在吃巧克力零食，事實上並不是），被騙的正是味覺。把比較句還原一次：the plain snack is tastier than it actually is，than 後面省略掉的是 it actually is tasty，比較的兩端是「感覺到的味道」與「實際的味道」，同一樣東西自己跟自己比。
larger（更大）是前一段那個裝置的效果，而這一句開頭 has also developed a special device 已經表示換了另一個裝置。prettier（更漂亮）講的是外觀，但 plain 和 scent bottles 兩個線索都指向味覺。healthier（更健康）在文章裡從頭到尾沒有提到營養或健康的改變。
tasty／tastier（美味的／更美味的）、plain（食物原味的、沒調味的；樸素的）、scent（氣味、香味）、visual trickery（視覺把戲）、make sb V（使某人做……，接原形動詞）、trick sb into Ving（騙某人做……）、than it actually is（比它實際上……）、be about to V（正要……）。
Researchers from a university in Japan have developed "diet-glasses" that play tricks with one's perception of food, which could be helpful to people on a diet.
A camera and a viewing system are built 26 these glasses. As the wearer brings the food toward their mouth, the camera captures an image of the food. It replays the image back through the glasses after processing it on an attached computer. The size of the food they are about to eat is magnified while 27 of their hand remains normal. Their brain is 28 tricked into thinking they are eating more than they really are. The study showed that participants who wore the glasses ate 9.3 less than those who did not wear them.
The team has also developed a special device which uses scent bottles and visual trickery to make the wearers of these glasses think that the plain snack they are eating is 29 than it actually is. The device, for instance, can be set to 30 one's favorite flavor. Recent experiments with this device showed that 80 of the participants were fooled by the smell. For example, some participants thought that they were eating a chocolate snack, but in fact they were not.