单项选择题
A．both sides of the brain are used equally B．the left side is fully developed C．scientists work on it D．the right side is fully developed
A．soccer and rugby B．American football and British football C．two village ball games D．two new football games
A．American football might develop in different places. B．American football is supposed to be changeable. C．American football will have its own rules. D．American football might see changes in the years to com