The phrase "compulsory to do" is grammatically correct and can be used in written English.
It means something that is required or mandatory to be done. Example: It is compulsory to do your homework before coming to class.
We pay for compulsory schooling to do that.
The mission of public schools and compulsory education is to do just that: create a responsible citizenry, so that it may govern itself.
I don't mind volunteering to take care of the building, but I think that making it compulsory for shareholders to do building work and fining them if they don't comply is outside the scope of our proprietary lease and possibly illegal.
The critic Jorge Brest has written that at one time all Argentine artists "had to do compulsory military service in Cubism".
Jobseekers have been made to do compulsory unpaid work for up to four weeks after refusing to take part in the voluntary work experience scheme.
A young analyst from a prominent Iranian family, he came to the United States as a boy, received dual citizenship, and attended college at Tufts, then returned to Iran to do compulsory military service.
When the initial efforts, attempted freestyle, go poorly, Annie gets a pair of inspirations: first, the couple should record (with Jay's new iPad) their exertions; second, they need to do compulsory routines, and she picks a choreographic script, pulling off the bookshelf their long-unconsulted copy of "The Joy of Sex" and proposing that they try, on camera, every one of its illustrated positions.
In South Korea, it is compulsory for young men to do up to two years of military service.
Participating physicians are obliged to do compulsory training in the field of diabetes management in advance as well as continuing education.
