Case 1: If f(a)=L, then what is the limit?
Case 2: If f(a)=(0/L) with L not equal to 0, then what is the limit?
Case 3: If f(a)=(0/0), then what is the limit?
Case 4: If f(a)=(L/0) with L not equal to 0, then what is the limit?

What is your difficulty with these problems? They are pretty much spelled out.