spread是哪個單詞的過去式

　　Prompt action was required as the fire spread.

　　由于火勢蔓延，須要立即采取行動。

　　The clouds had spread and covered the entire sky.

　　烏云鋪開，遮蔽了整個天空。

　　Fire spread rapidly after a chemical truck exploded.

　　一輛裝有化學品的卡車爆炸后火勢迅速蔓延開來。