1. I am having to do his work.
2. I was having to do his work.
3. I will be having to do his work.
Is it ok to use these form in general speaking english?
On second thoughts 1 is possible.
It's time for one of my rare disagreements with what bhai says.
The non-progressive form is nearly always correct, and is the safest choice for learners, but the progressive form is possible if the speaker wishes to draw attention to the limited duration of the obligation. There are 180 citations for the present and 140 for the past progressive forms in the British National Corpus.
There are only five citations for 'will be having to'. We appear not to use this form much.
Last edited by Matthew Wai; 18-Mar-2014 at 19:10. Reason: The source is added as 5jj said below.
It's also possible for an ongoing present sitatuon of limited duration: My wife is away this week, so I'm having to pour my own beer.
If you quote from a book, please cite your source, Matthew.
Last edited by Rover_KE; 18-Mar-2014 at 18:00.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.