be difficult to sb还是 be difficult for sb.? 到底该用哪个介词啊?

be difficult to sb还是 be difficult for sb.? 到底该用哪个介词啊? 是be difficult to sb 还是be difficult for sb? be rude to sb还是for sb be important to sb还是for sb be embarrassing to sb还是for sb? 到底是be harmful to sb.还是be harmful for sb.求用法 be dangerous to sb/be dangerous for sb哪个对? 是be free to sb 还是be free for sb 是be sorry for sb 还是be sorry to sb be free to sb 还是 be free for sb ..快速.. be important to sb.还是be important for sb. be patient ( ) sb.应该用哪个介词?