1)principle of anterior posterior development,前后发展原则2)principle of cephalocaudal development,前后发展原则3)principle of anteriorposterior development,前后发展原则4)QIAN(front)/HOU(back),前/后5)qian and hou,前后6)qian-hou,前-后7)qian,hou,前、后8)before and after,前后9)F/A,前后10)Fore and End Channel,前后导槽
