Rolls' studies show that______.A. we only need to eat soup at mealsB. we'd better eat soup at first or as the main mealC. we should eat soup as the last courseD. soup is often the most delicious food

本题考查对Rolls研究结论的理解，核心在于汤的摄入时机对饮食行为的影响。Rolls的研究表明，在正餐开始时或作为主餐摄入汤类，能够有效增加饱腹感，从而减少整体食物摄入量。因此，正确选项需体现这一关键结论。

选项分析

A. we only need to eat soup at meals

错误。该选项强调“只喝汤”，但研究并未否定其他食物的必要性，且“only”过于绝对化，不符合科学建议。

B. we'd better eat soup at first or as the main meal

正确。Rolls的研究明确指出，餐前或以汤作为主餐的一部分，能更快产生饱腹感，帮助控制热量摄入，与选项描述一致。

C. we should eat soup as the last course

错误。若将汤放在最后，可能因已摄入其他高热量食物而无法有效控制总热量，与研究结论矛盾。

D. soup is often the most delicious food

错误。该选项为主观评价，与Rolls的研究无关，且科学研究不涉及食物的主观美味程度。