non profit tax exemption 2. Leakage of gasoline pipe interface It is not obvious in some analyses, but it is important to note that economic profits include opportunity costs. The profit of an entrepreneur (normal profit) is usually positive, but economic profit can be either positive or negative (loss). That's why the opportunity cost is included: in a completely competitive market, when marginal cost equals marginal revenue, profit maximization or loss minimization conditions arise. If the market price is lower than the total average cost, which means that the economic profit is negative, the entrepreneur needs to compare the value of the loss and the average variable cost. If the business continues to operate, the negative economic profit must not be lower than the average variable cost, otherwise the entrepreneur would rather shut down the company than continue to take the loss. That does not stop Mr Draghi from warning that inflation is still being affected by a sluggish wage growth, which is now much slower than the "post-recession recovery". Gas vehicles mainly include liquefied petroleum gas vehicles (LPG vehicles or LPGV) and compressed natural gas vehicles (CNG cars or CNGV). As the name suggests, LPG cars are fueled by liquefied petroleum gas (LPG) and CNG is powered by compressed natural gas. The CO emission of gas vehicles is more than 90 percent less than the gasoline car, the hydrocarbon emission reduction is more than 70 percent, and the nitrogen and oxygen emission reduction is more than 35 percent, which is the current relatively practical low emission vehicle.