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 period

B、at the beginning and at the end of the seven week period

C、only once, at the beginning of the seven week period

D、twice to the men in Group A and once to the men in Group B

2).The post-exercise pulse rates of Group B were found on the average to have ()

A、not changed

B、gone down 28 beats per minute

C、gone down 30 beats per minute？

D、gone down 4 beats per minute

3).How many people were in each group？ ()

A、100

B、50

C、25

D、15

4).What did Group A in their program？ They ()every day.

A、stepped up and down on a bench

B、pushed and pulled on exercise handles

C、rode on an Exercycle

D、refrained from any exercise

5).When was pulse taken？ ()

A、After every exercise period

B、Every day

C、Every time the ratio of active riding was increased

D、After the step-test