Explanation:
Remember that 6/6 = 1, so we can use that knowledge to our advantage.
1/2 + 1/2 is one of them, because 1/2 + 1/2 = 2/2 = 1.
1/4 + 1/4 + 1/4 + 1/4 is one of them, because they equal 4/4 = 1.
1/3 + 1/3 + 1/3 is one of them, because they equal 3/3 = 1.