have a good time (to do) sth 还是 have a good time （doing) sth

doing老师说to dohave a hard time doing sth这是习惯用法 I had a good time listening to the music. He had a hard time trying to persuade her that her teacher was wrong.why did the teacher say:to do have a hard time doing sth?????????????建议再问一下老师.o