a)FALLif the roof, ceiling etc falls in, it falls onto the ground 〔屋顶、天花板等〕坍倒,塌下,垮掉SYN collapse
b)PMLINEto start walking or forming a line of people behind someone else 列队,集队
behind
His men fell in behind him.
他的手下在他身后集队。
Examples from the Corpus
fall in• During the hurricane the roof fell in.• The government is worried about the recentfall in house prices.• We need to fix the ceiling before it falls in on us.
fall behind• Caroline sighed and fell in behind him.• Ritchie quickly handed him his three wads of money and walked away, the rest of the possefalling in behind him.• The Tories have responded to calls for unity and fallen in behindJohnMajor.• A few shook themselves loose from the tangle, and poundedonward, others skirted the fallen and fell in behind them.