1.  fall in(v = verb.motion) break, cave in, collapse, founder, give, give way - break down, literally or metaphorically; "The business collapsed"; "The dam broke"; "The roof collapsed"; "The roof finally gave under the weight of the ice"; "The wall collapsed"; "The wall gave in"
Sample sentences: Somebody ----s; Something ----s

2.  fall in(v = verb.social) - to take one's place in a military formation or line; "Troops fall in!"
Sample sentences: Somebody ----s

3.  fall in(v = verb.social) get together, join - become part of; become a member of a group or organization; "He joined the Communist Party as a young man"
Sample sentences: Somebody ----s PP

VB  be in order, become in order, form, fall in, draw up, arrange itself, range itself, place itself, fall into one's place, take one's place, take one's rank, rally round, adjust, methodize, regulate, systematize.

VB  follow in a series, form a series, fall in, arrange in a series, collate, string together, file, thread, graduate, organize, sort, tabulate.

VB  happen, occur, take place, take effect, come, become of, come off, comeabout, come round, come into existence, come forth, come to pass, come on, pass, present itself, fall, fall out, turn out, run, be on foot, fall in, befall, betide, bechance, prove, eventuate, draw on, turn up, crop up, spring up, pop up, arise, show up, show its face, appear, come forth, cast up, supervene, survene, issue, arrive, ensue, arise, start, hold, take its course, pass off, meet with, experience, enjoy, encounter, undergo, suffer, pass through, go through, be subjected to, be exposed to, fall to the lot of, be one's chance, be one's fortune, be one's lot, find, endure.