Learn Python the hard way. 習題30. If和else/elif

#coding=utf-8
age = int(raw_input("Your age?"))

if age > 18:
 print "your age is", age
 print "You are an adult."
 
elif age > 12:
 print "your age is", age
 print "You are a teenager."
 
elif age > 6:
 print "your age is", age
 print "You are a kid."
 
else:
 print "your age is", age
 print "CHILDREN."

#note:

爲什麼這樣不可以？

if age > 18:

    print " your age is %d." % age

????