sb be doubtful 后面到底是用that从句还是用wether引导的从句

sb be doubtful 后面到底是用that从句还是用wether引导的从句 到底是be harmful to sb.还是be harmful for sb.求用法 It is ________(doubt) whether he will come.这句话的意思是不是 他到底会不会来值得怀疑?因为在 is 这个BE动词后面,所以应该用形容词doubtful 还有 这句话有什么其他语法点不 sth be accessible to sb 和sb be accessible to sth哪个对?我们老师说应该是sth be accessible to sb外面补课说是sb be accessible to sth哪个对啊?还有到底是sb be available to sth还是sth be available to sb? 是be difficult to sb 还是be difficult for sb? 是be free to sb 还是be free for sb be difficult to sb还是 be difficult for sb.? 到底该用哪个介词啊? buy sth 后面是跟to sb还是for sb? 到底是sb.face sth还是sth face sb be surprised at sth是对某事感到吃惊的意思,那如果at 后面是sb, Whether the work can be completed on time is doubtful.. find sb 后面是接doing还是?... sb.de frustrated什么意思是sb.be frustrated 关于There be sb/sth doing句型如果是过去时态怎么办?be动词要不要变成was、were?后面的doing怎么办? avoid啥意思,后面接动词怎么用,ing还是ed 还是to 还是原形/observe怎么用,啥意思.是win sb 还是 beat sb be 动词后面接 deep还是 deeply?deep into night 还是deeply into night? Be proud of sb是啥意思 是be interested in sth还是sb 英文语法：be sorry toor sb?是be sorry to sb还是be sorry for sb?