break语句用在while和for循环中，用于终止循环

if __name__ == '__main__':
    for i in range(10):
        if i == 5:
            break
        print(i)

if __name__ == '__main__':
    i = 0
    while i < 10:
        if i == 5:
            break
        print(i)
        i += 1