Past simpleSorry I'm late. I had to finish my math test.Present perfectShe's had to return to Korea at short notice.FutureYou'll have to work hard if you want to pass the exams.InfinitiveI don't want to have to go.Past simpleI couldn't/wasn't able to walk until I was 3 years old.Present perfectI haven't been able to solve this problem. Can you help?FutureI'm not sure if I will be able to come to your party.InfinitiveI would love to be able to play the piano.
