$4.$ Provide strings of size at elast $7.$ If no such string exists, just say $$non of size $>=7$ and give examples of any size.

For each of the following languages, give two strings that are members and two strings that are not members $$ a total of four strings for each part. Assume the alphabet sigma $=\{$a$,$ b$\}$ in all parts.

a$.$ a$*$b$*$

b$.$ a$($ba$)*$b

e$.$ sigma$*$a sigma$*$b sigma$*$a sigma$*$

f$.$ aba union bab