【中文版】

买空卖空是股市中的一种交易行为，指的是投资者在买卖股票时，并不持有实物股票，而是通过买卖股票合约来实现盈利。具体来说，买空是指投资者预测某只股票的价格将会上涨，于是先以当前价格买入该股票的合约，然后再在价格上升后卖出合约，从而赚取差价。而卖空是指投资者预测某只股票的价格将会下跌，于是先以当前价格卖出该股票的合约，然后在价格下降后买入合约，同样赚取差价。

买空卖空的风险在于，如果市场走势与投资者的预测相反，投资者将面临巨大的损失。因为买空卖空本质上是在借入股票并进行卖空或买入，这使得投资者在市场走势不利的情况下无法及时平仓，从而损失惨重。因此，在进行买空卖空交易时，投资者需要对市场走势有准确的判断和较强的风险承受能力。

除了股市中的买空卖空，在商品期货市场中也存在类似的操作方式，即买入期货合约后卖出，或者卖出期货合约后再买入，从而赚取差价。但需要注意的是，商品期货市场的交易品种和规则与股市不同，投资者在进行交易时需要充分了解市场规则和风险。

总之，买空卖空是一种高风险、高收益的投资策略，需要投资者具备丰富的市场经验和准确的判断能力。

【英文版】

What is buying and selling on margin?

Buying and selling on margin is a trading behavior in the stock market, which refers to investors buying and selling stocks without actually holding the physical stocks, but by buying and selling stock contracts. Specifically, buying on margin means that investors predict that the price of a certain stock will rise, so they buy the contract of the stock at the current price, and then sell the contract when the price rises, thus making a profit from the price difference. Selling on margin means that investors predict that the price of a certain stock will fall, so they sell the contract of the stock at the current price, and then buy the contract when the price falls, also making a profit from the price difference.

The risk of buying and selling on margin lies in that if the market trend is opposite to the investors' prediction, investors will face huge losses. Because buying and selling on margin is essentially borrowing stocks and selling or buying them, which makes investors unable to close the position timely when the market trend is unfavorable, resulting in heavy losses. Therefore, when buying and selling on margin, investors need to have accurate judgment of the market trend and strong risk tolerance.

In addition to the stock market, there are similar operating methods in commodity futures markets, which are buying and selling futures contracts to make profits from the price difference. However, it should be noted that the trading品种 and rules of commodity futures markets are different from those of the stock market. Investors need to fully understand the market rules and risks when trading.

In short, buying and selling on margin is a high-risk and high-return investment strategy that requires investors to have extensive market experience and accurate judgment.