bird of passage

1 migratory bird 候鸟. 2 (fig 比喻) person who passes through a place without staying there long 经某处而不久留的人.

biological, biological control, biological warfare (also germ warfare), biologically, biologist, biology, biomedical, bionic, bionics, biopsy, biorhythm, bioscope, biotechnology, bipartisan, bipartite, biped, biplane, birch, bird, bird of paradise, bird of prey, bird sanctuary, bird-bath, bird-song, bird-table, bird-watcher, birdbrained, birdcage wire, birdie, birdlime (also lime), birds, birdseed, biretta, Birmingham, birth, birth certificate, birth rate, birth-control, birthday, birthmark,