单项选择题 The isometric self-regulation of the myocardium regulates the pumping function of the heart by changing A、initial length of myocardium B、arterial pressure C、ventricular end-diastolic volume D、myocardial contractility

判断题 多股芯线剥去绝缘物后,芯线可能松散,应进行捻紧,以便浸锡和焊接() A、正确 B、错误

单项选择题 卤代烃的水解反应属于(    )反应A. 亲核加成B. 亲电加成C. 亲核取代D. 亲电取代