“Passengers not have their breakfast on the light train”. This rule arouses heated debates in Chongqing.
A. may
B. shall
C. can
D. should
网友回答
A. may
(答案→)B. shall
C. can
D. should
解析：句意：“乘客不得在轻轨上吃早餐。”这个规定在重庆引起了热烈的争论。shall在陈述句表示说话者的允诺、告诫、威胁、命令、规定、必然性等，主要用于第二、三人称。如：
1. You shall have a sweet. 你会吃到一块糖。(表允诺)2. You shall do as you please. 你可以随意行事。(表允诺)3. He shall suffer for this. 他将为此受苦。(威胁)4. Each petitor shall wear a number. 每个参赛者要戴一个号码。(表规定)，解题关键词：rule. 故B正确。