preheating of the mixture

例句：

1. 1.Before we start cooking, we need to preheat the oven.
   在我们开始烹饪之前，我们需要预热烤箱。
2. 2. The machine needs to be preheated before it can operate properly.
   这台机器在能正常工作之前需要预热。
3. 3.We should preheat the pan before putting in the food.
   我们应该在放入食物前预热锅。