So the QTUMs that ara avaliable to buy on exchanegs are basically IOU, not real QTUMs?
Yes - IOU's are available on the Chinese exchanges. Qtum has now released ERC20 tokens as a temporary solution until main net is launched in September. They are not listed on any exchanges at the moment.
The IOUs price has drop a lot compare to open price!
when the main net is launched,will the price pump ?
we are hope more than the higher price of the IOUs price
You can only hope. There is no way of knowing it.