• A. must be very boring
• B. some kind of recreation
• C. participating in them
• D. to relax oneself
• E. to choose one’s own way of relaxing
• F. maintain good health

To keep fit and enjoy life, all of us must have ______.

A．improvement
B．victory
C．failure
D．achievement

A．It can not be measured.
B．It can help people tolerate more pain.
C．It can be naturally released during physical activity.
D．It is related to a feeling of happiness.