Could you please check my pronunciation of /?/ and /u:/? I'm trying to correct my pronunciation

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For some reason, the audio feature didn't work on my PC (I'm looking into it), so I'll link to the audio files on my Windows Live Skydrive. I apologize for any inconvenience.
/?/http://cid-2017aeb917fd7137.office.live.com/self.aspx/.Public/shortu.mp3http://cid-2017aeb917fd7137.office.live.com/self.aspx/.Public/shortu1.mp3/u:/http://cid-2017aeb917fd7137.office.live.com/self.aspx/.Public/longu1.mp3http://cid-2017aeb917fd7137.office.live.com/self.aspx/.Public/longu.mp3Thanks a lot.