Convert each singular noun to plural, and each plural noun to singular.
(1) power
(20) beach
(2) dragon
(21) staple
(31 file
122)
trench
(4)
charm
(23) penny
(5) whiteboard
(24) company
puti
(6) wish
(25) dinner
(7) empty
(26) gallery
(8) tax
girl
19) daisy
(10)
disc
(30) library
(11) phone
(31) atrocity
(12) spy
(32) keyboard
(13) key
(33) party