英语语法inaugust,shewasstruckbyaveryheavystormduringwhichherrudderwastornaway.这里的which是什么用法?是一个定语从句吗?thisgreatlyreducedthespeedoftheship,fortherewasadangerthatifshetravelledtooquickl

　　英语语法

　　inaugust,shewasstruckbyaveryheavystormduringwhichherrudderwastornaway.这里的which是什么用法?是一个定语从句吗?

　　thisgreatlyreducedthespeedoftheship,fortherewasadangerthatifshetravelledtooquickly,thisrudderwouldbetornawayaswell.that后面引导什么从句?thisrudderwouldbetornawayaswell前加了逗号,整个句子不变成两句话了吗?