prepositions

Selectmytutor is not a native speaker of English and his responses are not reliable.

1. i am obliged ___to______ you ____for_______ your timely help.
2. what do you require ____of______ me ___(this was not prepared by a native speaker of English--there is no preposition which should be in this position.)______ in this case?
3. a man ____of_______ principles always adheres __to_____ his principles.

I am obliged to you for your timely help.

What do you require of me in this case. or What do you require from me in this case.

A man of principles always adheres to his principles.

The failure to capitalize the first words of the second and third sentences is further evidence that whoever prepared this quiz is not a native speaker of English.

Thanks @Setanta
would you please help me out in correction of this sentence as well.. just want to confirm..
None of the boys are doing their work.

whereas i know. it's going to be..

None of the boys is doing his work.