---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
网友回答
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。