She had no doubt as to the correctness of her own estimate.她对自己所作估计的正确性确信无疑。Local inhabitants haven't the slightest doubt as to who is the rightful owner.对于谁是合法所有人这个问题，当地居民已是确信无疑了。It was clear to him that Tolkien was a literary genius.托尔金是一位文学天才，这一点对他来说是确信无疑的。