Continuity: The variables in the problem are constantly changing. For example, the temperature of the bathtub in this year's Mercedes-Benz A question is constantly changing with time.

Discretization: The variable factors in the problem are discrete. For example, the treatment of space debris in MSE B problem this year is discrete.

Continuity and discreteness refer to the variables of the problem itself, which have little influence on solving problems and are mainly used to distinguish the types of questions.