The pairs are O-R (in CORP**O**-P-**R**ATE, 2 letters apart; in alphabet, P-Q-R, 2 letters apart), P-R (in COR**P**-O-**R**ATE, 1 letter apart; in alphabet, Q, 1 letter apart), and R-T (in CORPO**R**-A-**T**E, 1 letter apart; in alphabet, S, 1 letter apart). There are 3 such pairs. [cite: 5256, 5257, 5258, 5259, 5260, 5261, 5262, 5263, 5264]