Let the alphabet Sigma = {0, 1}. Write a regular expression for each of the following. In this question, you may not use the extended notation (only union, concatenation, and Kleene star). i. Bit strings that have an even number of 0's. ii. All words in which '1' appears tripled (and only tripled, meaning all 1's must appear in groups of three). The empty string is also accepted. iii. All bit strings that do not have substring '01'. iv. All bit strings that contain exactly two 0's or exactly three 0's