问题补充:
---What made the students so upset?
--- to go to the movie.
A. Having not been allowed
B. Not having allowed
C. Because of not having allowed
D. Not having been allowed
答案:
A. Having not been allowed
B. Not having allowed
C. Because of not having allowed
(答案→)D. Not having been allowed
解析:考查非谓语动词。句意:什么让这些学生们如此沮丧?——没有被允许去看电影。动名词做主语表示抽象动作,其否定式一般是在动名词前加not,本句中学生们是被允许的对象,用被动语态,故选D。