A：an underground lake was discovered
B：workers discovered an underground lake
C：there was an underground lake discovered
D：a lake was discovered underground
方程2x﹣1=3的解是（ ）
秦末农民战争爆发和秦朝灭亡的共同原因是（ ）
①一会儿有，一会儿无。形容隐隐约约的。____
②比喻人群的声音嘈杂喧闹，像烧开的水在锅里沸腾一样。____
③水势大，泛指广阔或壮大。____
④山倒塌，地裂开。形容声势巨大。____
