1)to and fro,来回地;往复地2)back and forth,来回3)come-and-go,来回4)one-round trip,走时来回5)social network,外来回族6)back and forth,来回次数7)French seam,来回缝8)return ticket,来回票9)double fare,来回票价10)reinforced stitches;reinforced seams,来回针
用法和例句
Since the middle of 1990 s,Chinese scholars began to analyse urban floating population using theory and methods of social network.