单项选择题
A.how nervous and aggressive people are. B.reaction to certain weather phenomena. C.the number of ions being generated by machines. D.the attitude of people to thunderstorms.
A.affects the performance of workers in restaurants. B.influences animal feeding habits. C.makes animals like hamsters more active. D.prepares humans for having greater leisure time.
A.They were less able to concentrate. B.Their body temperature fell too quickly. C.Their mental functions were immediately affected by the cold. D.They were used to swimming pool conditions.