一、if语句

#!/usr/bin/python 
 
n = 100 
 
if ( n  == 100 ) : 
	print ('right')
 
print ("exit!")

运行结果

二、if-else语句

#!/usr/bin/python

num=100
if num > 100:         
	print ('right')    
else:
    print ('wrong')         

运行结果

三、if-elif-else

#!/usr/bin/python

num = 70    
if num >=0 and num <= 10:           
    print ('num inside 0~10')        
elif num <=20:
    print ('num inside 11~20')
elif num <=30:
    print ('num inside 21~30')
elif num <= 50: