Question 2
A. 16 elderly people.
B. 16 young people.
C. 60 young people.
D. 60 elderly people.
Question 3
A. It had no side-effects.
B. It had no cost.
C. It was difficult to learn.
D. It needed a little training.
Question 4
A. Soft but fast music.
B. Rock music.
C. Punk music.
D. Soft and slow music.
Question 5
A little bit higher heart rate.
B. Psychological changes which was good for restful sleep.
C. Physical changes that aided restful sleep.
D. Less excitement during the day.
微信支付 
支付宝支付