在线学习高中课堂,上高中网课，学高中同步辅导课程，简单学习网涵盖高中多个版本课程，人教版、苏教版、北师版等，视频资源多层次辅导，基础-同步-冲刺，配套同类题、精品题、知识点讲解。
…there must have been several hundred people present just before the show began．……在演出开始前场内肯定已有好几百人了。
Those who failed to get in need not have felt disappointed, as many of the artistes who should have appeared did not come.那些没能进到场内的人没有必要感到失望，因为很多应该出场的专业演员都没有来。
must have 过去分词表示对过去发生的事进行推测（其否定式为can't have 过去分词，cf．第17课语法）；need have 过去分词表示过去不必做但实际已做了的事（cf．第41课语法）；should/ought to have 过去分词表示本来应该做而实际未做的事（cf．第65课语法）：
He had found five empty whisky bottles which the ghost must have drunk the night before.他发现了5只空的威士忌酒瓶子，这肯定是鬼魂前天晚上喝的。
The examiner must have been pleased with my performance.主考人对我的表现想必是满意的。
You needn't have said that.你没必要这么说。（实际已经说了）
You needn't have told him about my plans.你本不必把我的打算告诉他。（实际上已告诉了他）
He should have gone along a side street.他应该走一条小街。（实际上他走了主要街道）
