Unit 1 abnormal—apt

Unit 2 arc—blunder

Unit 3 blunt—chaos

Unit 4 characterize/-ise—concession

Unit 5 concise—cynical

Unit 6 damn—displace

Unit 7 disposition—engagement

Unit 8 enhance—flee

Unit 9 fling—grim

Unit 10 grin—incidence

Unit 11 incidentally—judicial

Unit 12 iunction—mechanism

Unit 13 medal—obligation

Unit 14 obscene—perplex

Unit 15 persistent—proposition

Unit 16 prose—refreshment

Unit 17 refuge—sculpture

Unit 18 seam—spectrum

Unit 19 speculate—swap

Unit 20 symmetry—tuck

Unit 21 tug—ward off