如何从使用python的列表中提取分子和分母？

fractions = [[1, 2], [3, 4], [5, 6]]

numerators = [fraction[0] for fraction in fractions]
denominators = [fraction[1] for fraction in fractions]

numerators = [1, 3, 5]
denominators = [2, 4, 6]

fractions = [[1, 2], [3, 4], [5, 6], [7, 0], ['a', 'b']]

def is_valid_fraction(fraction):
    return isinstance(fraction, list) and len(fraction) == 2 and all(isinstance(i, int) for i in fraction)

valid_fractions = [f for f in fractions if is_valid_fraction(f)]
numerators = []
denominators = []

for fraction in valid_fractions:
    if fraction[1] == 0:
        print(f"Error: Denominator cannot be zero in fraction {fraction}")
    else:
        numerators.append(fraction[0])
        denominators.append(fraction[1])

print("Numerators:", numerators)
print("Denominators:", denominators)