我为什么收到此消息无效的语法？

Question

我编写if语句，但是其中有错误。这是代码

mark = float(input('enter your mark : '))
if mark < 50:
    result = 'failed'
elif mark >= 50 and < 75:
    result = 'accepted'
elif mark >= 75 and < 85:
    result = 'good'
elif mark >= 85 and < 90:
    result = 'very good'
else:
    result = 'excellent'
print(result)

出现的消息是关于

Answer 1

正确的语法是elif mark >= 50 and mark < 75:或elif 50 <= mark < 75:

Answer 2

这将是您实际运行的代码：

mark = float(input('enter your mark : '))
if mark < 50:
    result = 'failed'
elif mark >= 50 and mark < 75:
    result = 'accepted'
elif mark >= 75 and mark < 85:
    result = 'good'
elif mark >= 85 and mark < 90:
    result = 'very good'
else:
    result = 'excellent'
print(result)

正如其他人所述，mark >= 50 and < 85在Python中无效。