带撇号的无效语法错误

Invalid syntax error with apostrophe

我今天一定是玩腻了,因为我在执行一个非常简单的任务时遇到了语法错误。

def hours_and_minutes_str(hours, minutes):
    """returns a string that represents the time span, including units

    number, number -> str"""
    return str(hours ' hours'  , minutes , " minutes")

感谢任何帮助。

缺少逗号

return str(hours, ' hours'  , minutes , " minutes")