评分标准模式

Common Mark Scheme Structure

Child Class Declaration (4–5 marks)

Mark	Criteria
M1	Correct class header: class Child(Parent):
A1	Correct __init__ method signature with all parameters
A1	Calls super().__init__(...) with correct parent parameters
A1	Initialises all new child attributes with self._attr = param

Method Override (3–4 marks)

Mark	Criteria
M1	Method signature matches parent exactly
A1	Calls super().method_name() at appropriate point
A1	Adds child-specific logic (new calculation / attribute use)
A1	Returns correct value (type matches parent)

Main Program with Inheritance (4–6 marks)

Mark	Criteria
A1	Instantiates parent object with correct arguments
A1	Instantiates child object with correct arguments
M1	Calls method on both objects to demonstrate polymorphism
A1	Outputs/uses the return values correctly
A1	Correct sequencing / loop structure if processing multiple objects

File Input + Object Creation (7 marks)

Mark	Criteria
M1	Opens file correctly (with open or open/close)
A1	Reads all lines / records in a loop
A1	Splits / parses each line correctly
A1	Conditional branch to distinguish parent vs child type
M1	Calls parent constructor with correct parsed arguments
A1	Calls child constructor with correct parsed arguments
A1	Stores all objects in a list and returns / processes them

Mark Scheme Keywords

Keyword	Meaning
M1	Method mark — awarded for correct approach
A1	Accuracy mark — awarded for correct implementation
B1	Independent mark — not conditional on M marks
Mark	More than one approach may be accepted
Accept	Alternative correct syntax is accepted
Not	Specific error that invalidates the mark
Ignore	Superfluous code is ignored (not penalised)

Common Mark Allocation Patterns

• Child class constructor: M1 + 3 × A1 = 4 marks
• Override method alone: M1 + 3 × A1 = 4 marks
• Main program: 2 × A1 + M1 + A1 + A1 = 5 marks
• File + constructor + override combined: M1 + A1 + M1 + A1 + 3 × A1 = 7 marks