should表义务的用法 — 英语选择题
题目
公园规定：游客离开时要把自己的垃圾带走。哪句话用 should 表达这项义务？ A. Visitors should take their rubbish with them. B. Visitors can take their rubbish with them. C. Visitors like taking their rubbish with them. D. Visitors are taking their rubbish with them.