i try to write this code to process Arabic language by python

 import codecs
 file = codecs.open("C:\Python27\CCA_raw_utf8.txt","r","utf-8")
 text= file.read()
 ####################################

 print "\n "," --------------------------------------------"

 text=text[1:]
 words=text.split()

 for w in words:
    if w == unicode ("?????","utf-8"):
    print w

but it doesn't and take error " if w == unicode ("?????","utf-8"): UnicodeDecodeError: 'utf8' codec can't decode byte 0xc7 in position 0: invalid continuation byte "

why program gives this result and how we can correct that??