Mark each of the following true or false.
_____ a. A group may have more than one identity element.

_____b. Any two groups of three elements are isomorphic.

_____c. In a group, each linear equation has a solution.

_____d. The proper attitude toward a definition is to memorize it so that you can reproduce it word for word as in the text. 

_____e. Any definition a person gives for a group is correct provided that everything that is a group by that person's definition is also a group by the definition in the text. 

_____f. Any definition a person gives for a group is correct provided he or she can show that everything that satisfies the definition satisfies the one in the text and conversely. 

_____g. Every finite group of at most three elements is abelian. 

_____h. An equation of the form a * x * b = c always has a unique solution in a group.

_____i. The empty set can be considered a group.

_____ j. Every group is a binary algebraic structure.