If you're making eggnog, custard, pudding, or ice cream, almost all recipes will start with scalded milk, or milk brought just to a boil. Whip your eggs in a heat-resistant bowl and go about the process of heating the milk over the stove according to the recipe you're using. For some recipes, you'll need to measure out the sugar into the eggs before you temper the eggs. If this is the case, measure it out and add it to the eggs. Whisk them together vigorously while the milk heats. Remove the milk from the heat after it's scalded and add a very small amount of milk to the heat-resistant bowl with the eggs and sugar in it. Use your ladle and spoon out about a tablespoon into your whipped eggs, whisking vigorously while you add. Make sure the eggs haven't curdled before adding more. If it helps, count to ten in between additions of milk, just to be sure you're not rushing it. That's slow enough that you'll probably be safe from curdling. Keep spooning the milk into the eggs, a little at a time, until you've transferred all the milk over to the egg bowl. Depending on what you're doing with the recipe, you might add this mixture to dry ingredients or chill it down for ice cream. Either way, you've tempered the eggs and you're ready to move forward with the recipe.

TL;DR in Chinese:
在炉子上煮沸牛奶。 在鸡蛋里加入适量的糖。 先加几勺牛奶。 继续添加，直到所有的牛奶都被加入。