I agree with this many exchanger cannot be trusted my friend already send coin to other exchange but there is no coin receiving in her wallet,

always take care when you send your coin to other exchanges.
It is not about trusting all the time, though trust is also something should be in mind but in most cases exchanges get hacked by evil users of internet, so that is why keeping all your coins in a exchange is not safe.
That is the reason I keep most of the bitcoin in my own wallet. I just leave some in the exchanges to trade.