She had no luck finding a job.为什么用LUCK不用LUCKY

She had no luck finding a job。意思是,她寻找工作并不是很幸运。但这是为了在汉语里语句通顺才这么翻译,这里的幸运,应该是名词,所以用 luck。如果句子是She isn't lucky with finding a job。这里就是形容词了。