是否有have a difficulty doing sth.It's difficult to do sth.It's

是否有have a difficulty doing sth.It's difficult to do sth.It's a good time to do sth.
have a good time doing sth.
have problem doing sth.
have a difficult time doing sth.的形式?
还有,a good time是名词吗?
如果有上述形式,和a good time是名词的话,我可否总结成：It's +n.+to do sth.It's +adj.+to do sth.
have +n.+doing sth