happen to do sth与do sth by accident一样吗

happen to do sth与do sth by accident一样吗 happen to do sth 4,happen to do sth sb.happen to do sth. by to do sth=by doing sth吗 use sth.to do sth.和do sth.with sth.意思一样吗 help do sth与 help to do sth意思一样吗? help sb do sth与help sb.to do sth.意思一样吗 it happen to sb that 和 sb happen to do sth 表达的意思一样么 sb.happen to do sth.意思辨析 happen to do sth什么意思 happen to do sth的汉语是什么?