readline skips on line

[Soundwave]

I got a part of a programm looking like this

f=open('test.txt', 'r')
while f.readline()!='':
    print f.readline()
print 'ready'

but when it is runned, it wil print out the lines in the text file, but it
skips all the the odd line, it only displays line 2,4,6,8,10 and further

How can I solve this problem ?