Read the following text and fill each of the numbered spaces with ONE suitable word.

Read the following text and fill each of the numbered spaces with ONE suitable word.

Write your answers on ANSWER SHFFT l.

Walking-like swimming，bicycling and running--is an aerobic exercise，(31)___builds the capacity for energy output and physical endurance by increasing the supply of oxygen to skin and muscles.Such exercises may be a primary factor in the(32) ___0f heart and circulatory disease.

As probably the least strenuous，safest aerobic activity，walking is the(33) ___acceptable exercise for the largest number of people.Walking(34)

___comfortable speed improves the efficiency of the cardio respiratory system(35) ___stimulating the lungs and heart，but at a more gradual rate(36) ___most other forms of exercise.

In one test，a group of men 40 t0 57 years of age，(37) ___at a fast pace for 40 minutes four days a week，showed improvement(38) ___to men the same age on a 30 minute，three—day—a—week jogging program in the same period.Their resting heart rate and body fat decreased(39) ___.These changes suggest(40) ___of the important-even vital--benefits walking can(41) ___about.