Each of the six-letter words in this puzzle has the two middle letters missing. The same two letters are missing from the three words in each numbered set. Determine what two letters are missing from each set. For example, consider these three words:

Insert "UI" into each word to form bruise, fruity, and squirm. The hints give you more words in the same set; the same two letters are missing.

1.  B R _ _ R S
    T R _ _ L S
    O P _ _ T E

2.  W E _ _ E D
    B E _ _ E R
    H E _ _ E N

3.  A M _ _ L E
    I M _ _ G N
    D E _ _ T Y

4.  D E _ _ C E
    I N _ _ N T
    U N _ _ I R

5.  B O _ _ N G
    U N _ _ S E
    R E _ _ R E

6.  C O _ _ E D
    H U _ _ L Y
    T I _ _ R E