Baseball is the oldest pastime in American history.After years of evolution,todays baseball games are played with nine players,each serving a different role.The pitcher and the catcher are the first line of defense for the team in the field.棒球是美国历史上最早的休闲活动。经过多年的演变，今天的棒球是由9个运动员上场来比赛，每个人负责不同的任务。在球场上，投