Python3.3:下面代码第7行中的无效语法错误

Question

以下是代码：

Weight = float(input("Enter weight in Kilograms: "))
Height = float(input("Enter height in meters: "))
BMI = (Weight / (Height**2))
print ("%.2f" %BMI)
if BMI < 18.5:
    print ("You are under weight")
elif BMI >= 18.5 and < 25.0:
    print ("You weight is normal")
elif BMI >= 25.0 and < 30.0:
    print ("You are overweight")
elif BMI >= 30.0:
    print ("You are overweight")

在elif >= 18.5和<25.0行中获取无效语法：

Answer 1

>、<和其余的是二进制运算符。它在两边寻找一个操作数，当它在左边找到一个关键字时，and < 25.0抛出一个SyntaxError。

通常这样做的方法是：

if BMI >= 18.5 and BMI < 25.0:

但有一条解决不平等问题的捷径：

if BMT < 18.5:
    # underweight
elif 18.5 <= BMI < 25.0:
    # normal
elif 25.0 <= BMI < 30:
    # overweight
elif 30 <= BMI:
    # super overweight