In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.

The series employs a panel of four coaches who critique the artists' performances and guide their teams of selected artists through the remainder of the season. They also compete to ensure that their act wins the competition, thus making them the winning coach. Members of the coaching panel include Adam Levine, Blake Shelton, Christina Aguilera (seasons 1 -- 3, 5, 8, 10), CeeLo Green (seasons 1 -- 3, and 5), Shakira (seasons 4 and 6), Usher (seasons 4 and 6), Gwen Stefani (seasons 7, 9, and 12), Pharrell Williams (seasons 7 -- 10), Miley Cyrus (seasons 11 and 13), Alicia Keys (seasons 11 -- 12, and 14), Jennifer Hudson (season 13), and Kelly Clarkson (season 14).
who have been the judges for the voice