As soon as the Keeper asked that question, Shang was thrown into a problematic situation again.
Yes, he was supposed to trust them and tell them truthfully about his powers, but he couldn't possibly tell them the real truth right now.
Obviously, Shang decided to go with Addition and Subtraction first since that represented the concept of Entropy better. Additionally, the contrast between Addition and Subtraction made it more fitting for a dual wield style. Twilight and Temperature didn't fit very well.
Lastly, comprehending Temperature would have been extremely difficult since Shang would be focusing on two Elements that weren't related to his Affinity.
Addition was related to Shang's supposed Twilight Affinity since it included light.
Subtraction was related to Shang's supposed Twilight Affinity since it included darkness.
But Temperature?
Fire and Ice?
How was that related to Light and Darkness?
