[ابو بيشو]

I have to catch up all the lessons I missed.
I have to catch up on all the lessons I missed.
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catch up (on/with sth) = do the things that you should have done before
so that your work is up to date: 'Why don't you stay at home tonight and
catch up on some of your homework?'
Compare: 'Don't get too far behind with your homework or you'll never be
able to catch up.'