Similar words: date back to, backtrack, back to back, back-to-back, go back to, bounce back, racetrack, spacebar.
31. Study carefully its origin, can roughly trace back to primitive human era. But the concept of informal group is put forward by modern management educational circles correspondent to formal group.
32. Be able trace back to - suppliers ( slaughter houses ), delivery date of raw materials and other related info.
More similar words: date back to, backtrack, back to back, back-to-back, go back to, bounce back, racetrack, spacebar, comeback, come back, die back, bareback, sebaceous, take back, date back, move back, give back, drive back, horseback, on the back of, double back, strike back, linebacker, stickleback, to the backbone, sebaceous cyst, sebaceous gland, a stab in the back, backspace, horseback riding.