All of the riffs studied so far have used moveable fingerings which enable you to play them in any key. However, there are many riffs which make use of open strings, particularly in the keys of A and E. Here is the riff from Example 49, this time played in the second position and making use of the open strings.
Here is the same riff in the key of E, with a slight variation at the end. Try creating some of your own riffs making use of the open strings.