Q1. What is the passage mainly about?

1. AHow to make a sweet dessert
2. BWhy we can still eat dessert when we are full
3. CWhy Japanese people eat a lot of rice
4. DHow our stomach makes food

満腹でもケーキが食べられる「別腹」の理由を説明しているので B。

Q2. According to the passage, what happens when you eat one food again and again?

1. AYou get a second stomach.
2. BAll foods taste bad.
3. CYou want to eat more of the same food.
4. DYou get tired of that taste only.

you get tired of that taste only とあるので D。ほかの味はまだおいしく感じる。

Q3. In this passage, "get tired of" a taste means ...

1. Ato sleep after eating
2. Bto cook it for a long time
3. Cto stop enjoying it as much
4. Dto like it more and more

get tired of ～ は「～に飽きる」。その味をあまり楽しめなくなることなので C。

Q1. What did the participants in Rolls's 1981 study do?

1. AThey ate many foods and then exercised.
2. BThey chose their favorite dessert.
3. CThey rated foods, ate one food, and rated the foods again.
4. DThey ate yogurt every day for a month.

食べ物を評価 → 1種類だけ食べる → もう一度評価、という手順が書かれているので C。

Q2. What happened to the foods the participants had NOT eaten?

1. AThey became much less pleasant.
2. BTheir pleasantness did not change much.
3. CThey became the participants' favorite foods.
4. DThey were thrown away.

the other foods did not change much とあるので B。大きく下がったのは食べた食べ物のほう。

Q3. What does the writer mean by "its calories still count"?

1. ADessert has no calories.
2. BPeople should count their food every day.
3. CDessert is healthier than the main dish.
4. DThe energy from dessert is still added to what you eat.

別の胃に入るわけではないので、デザートのカロリーも摂取量に加わる、という意味なので D。

Q1. Which statement best summarizes the passage?

1. AHumans really have two stomachs, one for dessert.
2. BEating a variety of foods always leads to weight loss.
3. CSweet foods never make people feel full.
4. DWe lose interest in the specific food we eat, which helps explain room for dessert but may also encourage overeating.

食べた食べ物にだけ飽きる仕組み（感覚特異性満腹）が別腹を説明し、現代では食べすぎにもつながりうる、という全体の流れなので D。

Q2. According to the passage, what was the original benefit of sensory-specific satiety?

1. AIt helped people sleep after meals.
2. BIt made sweet foods taste stronger.
3. CIt encouraged people to eat a range of foods and nutrients.
4. DIt helped people lose weight quickly.

this mechanism originally encouraged humans to consume a range of foods and therefore a range of nutrients とあるので C。

Q3. Why does the writer say "some caution is needed"?

1. ABecause the studies were carried out on animals only
2. BBecause the classic studies were short and did not directly measure long-term weight
3. CBecause no one has repeated the 1981 experiment
4. DBecause dessert has fewer calories than people think

short laboratory experiments that did not directly measure long-term body weight と研究の限界が示されているので B。