Extension cord question

[shakeel1]

So I have this white extension cord coming from the rooftop, on the cord there's a deep cut that shows a black thing inside,(probably a wire). Is it safe to use? Here's a pic: http://imgur.com/PdwFHP1

 

[impsquared]

Probably, but before you use it wrap the cut in electrical or duct tape

 

[ShadyHamster]

Is it safe to use? No.
Will it work? Probably.
Should you use it? Not really.