Find an RE for all strings of bs with at least two bs. Since a string here can have any length except 0 or 1, the language is infinite, which suggests the use of closure. To get lengths of at least 2 we start with lengths of at least 0, for which we can use b*, and then increase all lengths by 2, by adding bb. That is, b*bb is an RE for the strings of at least two bs. The extra bs could have been added anywhere: bbb* bb*b = b*bb are all correct answers. Note that each * applies only to the b right before it, according to the precedence rules. =