[
    {
        "question_types": [
            "expression_conversion",
            "equivalence_validation",
            "expression_simplification"
        ],
        "variables": [
            "a",
            "b",
            "c"
        ],
        "cities": [
            "Beijing",
            "Guangzhou",
            "Shenzhen"
        ]
    },
    {
        "question_types": [
            "expression_conversion",
            "equivalence_validation",
            "puzzle_solution"
        ],
        "variables": [
            "p",
            "q",
            "r"
        ],
        "cities": [
            "Suzhou",
            "Shanghai",
            "Hangzhou"
        ]
    },
    {
        "question_types": [
            "expression_conversion",
            "truth_table_completion",
            "puzzle_solution"
        ],
        "variables": [
            "p",
            "q",
            "r",
            "s"
        ],
        "cities": [
            "Shanghai",
            "Beijing",
            "Guangzhou"
        ]
    }
]