Give regular expressions generating the languages

a) {w | w has length at most 3 and its second symbol is a 1}

b) {w | w contains exactly one zero and two ones}

c) {w | every 0 in w must be followed by at least one 1}

d) {w | every odd position of w is 0}

e) {w | w contains an even number of 0s, or contains exactly two 1s}