Regular Expressions Exercise: Write regular definitions for the following languages: All strings that end by "at" such as: {cat, rat, mat, at, bat, hat, .... } All strings that start by Z letter All strings that start by A or B or none of these two letter followed by C. Think about this: All strings of a's and b's that do not contain the substring abb. All strings of a's and b's that do not contain the subsequence abb. All strings of a's and b's with an even number of a's. All strings of a's and b's with and odd number of b's. All strings of a's and b's that contain at least two b's. All strings of a's and b's that contain at most two b's. All strings of a's and b's that contain just two or three b's