Trading prices on both sides of the bid-ask spread, traders (or online trading system) will be reported, for example, 1529.3 / $ 9.8, then $ 1529.3 is the prevailing ask price, $ 1529.8 is the current bid price. If investors want to buy gold, the price should be $ 1,529.8 instead of $ 1,529.3; Conversely, if investors want to sell gold, the price should be $ 1,529.3 $ 1,529.8. Similarly, investors under the orders of whether transactions have to depend on the price is the same-day orders for the bid or ask price, for example, under a $ 1,510.0 investors to sell a gold, the highest price on the date of 1509.8 / 1510.3 dollars, the highest ask price is only $ 1509.8, so the order is not traded; another example investors under a $ 1,520.0 buy two gold intraday orders, such as the lowest price on the day to $ 1522.5 / 3.0, then the minimum The bid price is only $ 1522.5, so the order is not traded.