你根据此步骤来分析先把该句还原成肯定句,fishingisthewriter'sfavoritesportbecauseit'sfun.（假设原因becauseit'sfun是这个）该肯定句变一般疑问句是把be动词即is提前：Isfishingthewriter'sfavoritesportbecauseit'sfun?因为你是针对原因becauseit'sfun提问,所以提问应是Why,在一般疑问句Isfishingisthewriter'sfavoritesportbecauseit'sfun基础上,把becauseit'sfun去掉,Why提至句首,则变为whyisfishingthewriter'sfavouritesport?不知道这样讲你能理解不?