To Study & Verify Half and Full Subtractor

Half subtractor is used to perform subtraction of ____________
For subtracting 1 from 0, we use to take a _______ from neighbouring bits.
How many outputs are required for the implementation of a subtractor?
Let the input of a subtractor is A and B then what the output will be if A = B?
Let A and B is the input of a subtractor then the difference output will be ___________