面粉、水和酵母的混合物然后被放在温暖的地方四个小时。

The ___mixture of flour, water and yeast is then left in a warm place for four hours.

向混合物中加入牛奶，搅拌至顺滑。

Add milk to the ___mixture and stir until smooth.

她为实验准备了一种化学混合物。

She prepared a chemical ___mixture for the experiment.