二价的

例句：

1. 1. The salt is 20% sodium and 80% potassium.
   这种盐含20%的钠和80%的钾。
2. 2. This type of alloy has a specific melting point, which makes it useful for certain applications.
   这种合金有特定的熔点，因此在某些应用中非常有用。
3. 3. The chemical reaction between the two elements is known as neutralization.
   两种元素之间的化学反应称为中和反应。