. The so-called single-line trading means buying short positions (or short positions) when you are optimistic about a certain currency, and selling short positions (short positions) when you are bearish on a certain currency. If the judgment is correct, the profit will naturally be more; But if the judgment is wrong, the loss will be greater than hedging. The so-called hedging is to buy a foreign currency at the same time and short it. Besides, we should also sell another currency, that is, short selling. In theory, shorting a currency and shorting a currency should be the same as the silver code, which is the real hedging, otherwise the hedging function cannot be realized if the two sides are different in size. This is because the world foreign exchange market is based on US dollars. All foreign currencies rise and fall with the US dollar as the relative exchange rate. A strong dollar means a weak foreign currency; If the foreign currency is strong, the dollar will be weak. The rise and fall of the dollar affects the rise and fall of all foreign currencies. Therefore, if you are optimistic about a currency, but want to reduce the risk, you need to sell a bearish currency at the same time. Buy strong currency and sell weak currency. If the estimate is correct, the dollar will weaken and the strong currency bought will rise. Even if the estimate is wrong and the dollar is strong, the currency bought will not fall too much. The weak currency sold has fallen sharply, with less losses and more gains, and it can still be profitable on the whole.