定语从句中把whose换成of which,of which应该放在什么位置?是先行词之后还是再往后的位置?

定语从句中把whose换成of which,of which应该放在什么位置?是先行词之后还是再往后的位置?She is looking after the child whose parents have gone to London这句话中如果把whose改为 of which,应该把of which放在哪,下面的哪句是对的?She is looking after the child of which the parents have gone to LondonShe is looking after the child the parents of which have gone to London还有这句话The house whose roof was damaged now has been repaired完全一样的一句话,在两个网页上看到两种不同的说法The house of which the roof was damaged has now been repairedThe house the roof of which was damaged has now been repaired难道是两种说法都对吗?of which 放在两个不同的位置一点区别都没有吗?the person from whom the message came did not say his name送来信的人没有说他的名字这句话是薄冰的语法书上的例句,from whom可以往后放吗,改成下面这样可以吗?the person the message came from whom did not say his name