It is +形容词+不定式/动名词+.这种句式中,请问哪种情况下只能用动名词,不能用不定式?

这种句型,通常都是用不定式to do的.在下列句型中用动名词doing：It's a lot of /great fun doing sthIt's no use doing sthIt's a waste time / money doing sth It's no good doing sthIt's no point doing sth谨祝...