be useful to

对…有益

be sure of oneself, be surprised at, be suspicious of sb., be suspicious of sth., be taken with sb/sth, be tempted to do, be thick with, be tired of, be to blame, be to blame for, be to do sth., be tolerant of, be true of, be true with, be typical of, be unable to, be unaware of, be up against, be up to, be used to, be very useful at, be willing to, be witness to, be worth doing, be-, beach, beach buggy, beach-ball, beach-head, beachcomber, beachwear, beacon, bead, beadle, beady, beagle, beagling, beak, beaked, beaker,