中文：

阴阳合同是指合同当事人就同一事项订立两份以上的合同，以满足不同的法律要求。其中，一份是阳合同，是公开的、合法的；另一份是阴合同，是私下的、不合法的。

阴阳合同通常被用于逃避税收、掩盖非法行为等目的。例如，在房屋买卖中，卖方可能会与买方签订一份阳合同，约定房屋售价为100万元，但实际上双方私下签订的阴合同中约定房屋售价为150万元。这样，卖方可以通过阴阳合同逃避一部分税收，而买方也可以通过阴阳合同获得更多的利益。

阴阳合同是一种违法行为，不仅会对合同当事人的利益造成损害，还会破坏市场秩序和公平竞争。因此，我们应该坚决反对阴阳合同这种行为，并积极配合相关部门进行打击。

英文：

Yin-Yang contract refers to the contracting parties entering into two or more contracts for the same matter to meet different legal requirements. One is the Yin contract, which is private and illegal; the other is the Yang contract, which is public and legal.

Yin-Yang contracts are usually used for purposes such as tax evasion and concealing illegal behavior. For example, in a house sale, the seller may sign a Yang contract with the buyer, agreeing on a selling price of 1 million yuan, but in reality, a Yin contract signed privately between the two parties stipulates a selling price of 1.5 million yuan. In this way, the seller can evade some taxes through the Yin-Yang contract, while the buyer can also obtain more benefits through the Yin-Yang contract.

Yin-Yang contracts are illegal acts that not only cause harm to the interests of the contracting parties, but also破坏 market order and fair competition. Therefore, we should firmly oppose the practice of Yin-Yang contracts and actively cooperate with relevant departments to crack down on it.