]
这句话的主要支架是:An ice storm had turned the decks into frozen sheets
意思是:一场冰暴已经把甲板变成了一张结冰的被单.当船翘起,开始下沉的时候,甲板上几百个家庭都掉入了海里.
"that sent hundreds of families sliding into the sea "是修饰"decks"的.至于是什么成分的句子,这个我不擅长说清..
as the ship tilted and began to go down" 是个状语从句..表示一个状态.