be down for sb

be down for sb be sth for sb be vailable for sb. be true for sb. be useful to sb还是for sb? be embarrassing to sb还是for sb? be important to sb还是for sb be rude to sb还是for sb be left for sb to be valuable for sb对吗 be important to sb.还是be important for sb.区别? 是be difficult to sb 还是be difficult for sb? be adj to sb 与be adj for sb 区别 be free to sb 还是 be free for sb ..快速.. be free to sb还是be free for sb 是be free to sb 还是be free for sb 什么时候be+形容词+for sb,什么时候be+形容词+to sb be/keep/remain calm 和 calm sb.down的区别