72. The author of the report (对医院的问题非常了解)because he has been working there for many years.
73. The father (哀求)his son to be less trouble to his mother.
74. The murderer (混在人群当中)with an attempt to shoot at the Prime Minister whenever he seized a chance.
75. (为了最大限度减少窃案发生的`可能性), install a good alarm system.
76. Scientists will have to (提出增加世界粮食供应量的新方法).
答案与解析： 72. is well acquainted with the problems in the hospital
73. pleaded with
74. mingled with the crowds
75. To minimize the risk of theft
76. come up with new methods of increasing the worlds food supply
