Fifty volunteers were alphabetically divided into two equal groups. Group A is to partic
ipate in a 7-week exercise program and Group B is to avoid planned exercise of any sort during those 7 weeks. On the day before the exercise program began, all 50 men participated in a step-test. This consisted of stepping up and down on a 16-inch bench, at 30 steps a minute for 5 minutes. One minute after completion of the step-test, the pulse rate of each subject (被测试者 ) was taken and recorded. This served as the pretest for the experiment. For the next 7 weeks, subjects in Group A rode an Exercycle (机器脚踏车 ) for 15 minutes each day, while Group B remained doing no planned exercises.At the end of the 7 weeks, the step-test was again given to both groups of subjects, and their pulses taken. The post-exercise pulse rates of subjects in the experimental were found to have decreased an average of 30 heart beats per minutes, with the lowest decrease 28 and the highest decrease 46. The pulse rates of subjects in the control group remained the same or changed no more than 4 beats, with an average difference between the initial and final tests of zero.1).The step-test was given ()A、after each exercise periodB、at the beginning and at the end of the seven week periodC、only once, at the beginning of the seven week periodD、twice to the men in Group A and once to the men in Group B2).The post-exercise pulse rates of Group B were found on the average to have ()A、not changedB、gone down 28 beats per minuteC、gone down 30 beats per minute？D、gone down 4 beats per minute3).How many people were in each group？ ()A、100B、50C、25D、154).What did Group A in their program？ They ()every day.A、stepped up and down on a benchB、pushed and pulled on exercise handlesC、rode on an ExercycleD、refrained from any exercise5).When was pulse taken？ ()A、After every exercise periodB、Every dayC、Every time the ratio of active riding was increasedD、After the step-test
