pta按要求编写一个类car

在Python中，我们可以创建一个名为`Car`的类，用于表示汽车的基本属性和行为。以下是一个简单的`Car`类的示例：

class Car:
    def __init__(self, brand, model, year):
        self.brand = brand
        self.model = model
        self.year = year
        self.speed = 0  # 初始速度

    def start_engine(self):
        print(f"{self.brand} {self.model} started.")

    def accelerate(self, speed_increase):
        if speed_increase > 0:
            self.speed += speed_increase
            print(f"{self.brand} {self.model} is now at {self.speed} km/h.")
        else:
            print("Invalid speed increase.")

    def stop(self):
        self.speed = 0
        print(f"{self.brand} {self.model} stopped.")

# 示例如何使用Car类
my_car = Car('Toyota', 'Corolla', 2022)
my_car.start_engine()
my_car.accelerate(50)
my_car.stop()