Each word in a group can be prefixed with the same one-, two-, or three-letter prefix. Find the prefix that works in each group. Warning: the meaning of the word always changes radically when the prefix is applied.

1.   Be, fit, fuse, cured, found
2.   In, met, arse, pious, median, unties
3.   Do, men, ward, verse, trophy
4.   Lo, bit, shed, track
5.   Ad, age, vial, fling, cornered