【问】 (1) “Wasn't Joan supposed to be here by now?”
 “Don't worry，she'll be here______twenty minutes. ”
 A. by at least B.around C. nearby D. in about(TOEFL，72. 6;74. 3)
 (2) “Why can't you and Bill go to the movies tonight?”
 “We are________a history test tomorrow. ”
 A. supposed to having B. supposedly to have
 C. supposed to have D. supposedly to having(TOEFL，73. 10)
 (3) You're supposed to be an expert.
 我对上面三句中的be supposed的意义和用法很不理解。请分析。
 【答】 be supposed最常见的用法有二。
 A.be supposed to用作半助动词，其语法特点同have to，be about to，be bound to，be going to一样：其语义相当于ought to，表示按照规则、规律、义务或约定“应当”、“理应”去做某事。
 1. People under eighteen aren't supposed to buy alcoholic drinks.
 十八岁以下的人不应买含酒精的饮料。
 2. You' re not supposed to know that.
 你不应该知道那事。
 3. He is supposed to arrive at six o'clock.
 他应该六点钟到达。
 4. The machine is not supposed to make noise.(《韦氏辞典》，电子版)
 这台机器不应当产生噪音。
 5. She was supposed to meet me here. (同上)
 她应当在这里接我。
 6. He told this to somebody else，not realizing that he was not supposed to. 他不知道这些话不该告诉别人，结果告诉别人了。
 be supposed to如果与完成时不定式连用，则表示“本应该做某事而实际上却没有做”。例如：
 1. He was supposed to have told me about it.
 他本应该把这件事告诉我的。
 2. Mrs. Brown is supposed to have left for Italy last week.
 布朗太太本应上周动身去意大利的。
 B. be supposed to作“被认为”、“被看作是”解(往往暗含着“事实并非如此”的意思)。例如：
 1. You're supposed to be an expert，but you don't know very much about it，do you?(NCE)
 大家都认为你是个专家，可是你并不在行，是不是?
 2. Wives tend to believe that their husbands are infinitely resourceful and versatile. Evenhusbands who can hardly drive a nail in straight are supposed to be born electricians，carpenters，plumbers and mechanics. (NCE)
 作妻子的常常把自己的丈夫看得聪明能干，多才多艺。即使连钉子也钉不直的丈夫.也会被看作是天生的电工、木工、管道工和机修工。
 3. On another occasion，he invited a number of important critics to see his private collection of modern paintings. This exhibition received a great deal of attention in the press，for though the pictures were supposed to be the work of famous artists，they had in factbeen painted by Dickie. (New Concept English，Book 3，P.80)
 ……这次展览在报界引起了极大的反响，因为这些曾经被艺术评论家们看作是著名画家作品的油画，实际上却是迪基自己画的。
 4. Everyone went to the funeral，for the ‘ghost’ was none other than Eric Cox，a thirdbrother who was supposed to have died as a young man. (New Concept English，Book3，L. 30)
 大家都去参加葬礼，因为“幽灵”不是别人，而是考克斯的第三个兄弟，叫埃里克·考克斯。人们都以为他在年轻时就已经死了。