76. Why should girls play sports/ Reasons why girls should play sports (take exercise)
77. (l)improve/improving learning; (2) improve/improving memory; (3) improve/improving concentration
78. help you (a lot)/benefit you/be helpful to you/serve you well/do you good
79. 体育运动还是一项感觉良好的运动，因为运动能帮助女孩们保持体形，维持健康的体重，还能帮她们交到新朋友。
80. The brain chemicals released and the friends made during exercise.
