Ad hoc personality means that in order to protect a scientific theory from the danger of being disproved, the theory is modified or some new assumptions are added so that the theory is not provable or testable. Which of the following are ad hoc modifications:. ['The scholars of the Ptolemy system have continuously increased the number of rounds in order to make the "geocentric theory" consistent with the observed data of celestial bodies. By the 16th century, the total number of rounds of the Ptolemy system has increased to 80.', "Aristotle's followers insisted on the doctrine that all celestial bodies are perfect spheres, and proposed that the undetectable matter existing on the moon is full of recesses, so that the moon still maintains a perfect sphere shape.", "Einstein modified Newton's absolute space-time system in order to study particularly large and fast objects, and proposed a relative space-time system, which includes the theory of invariance of light speed and the theory of variable mass.", 'Riemann et al. Created non-Euclidean geometry by modifying the fifth axiom of Euclidean geometry, taking mathematics a step forward.']