Let w $=$ abba over the alphabet $\{$a$,$b$\}$

a$.$ List the prefixes of w

b$.$ List the proper prefixes of w

c$.$ List three strings that are substrings of w

d$.$ Give the shortest string that is a substring of w$.$

e$.$ Give one string y so that w is a proper substring of y$.$

f$.$ Give one string smaller than w

g$.$ Give one string larger than w