一下子: all at onceall of a suddenat a draughtat a timeat one blowin a short while
啪: 象声词(形容放枪、拍掌或东西撞击的声音) bang; crack; clap 短语和例子啪地一声合上书 shut a book with a clap; 啪! 鞭子一挥。 crack! went the whip. 啪的一声放了一枪。 the gun went off with a bang. 气球啪的一声爆炸了。 the balloon burst with a bang
