gong1 / ren2 / zheng4 / zai4 / jun4 / xie4 / he2 / dao4 / yi3 / bao3 / zhang4 / hang2 / yun4 / chang4 / tong1工人正在浚渫河道,以保障航运畅通。Workers are dredging the river channel to keep shipping unobstructed.