2019年12月大学英语六级第一套真题及答案_2019年12月大学英语六级阅读晨读美文：OilandWater

【#四六级考试# 导语】®文档大全网英语四六级频道为备考英语六级的同学们整理了2019年12月英语六级阅读晨读美文：Oil and Water ，希望可以为大家带来帮助，预祝大家高分通过大学英语六级考试。

　Oil and Water

　　To understand the emulsifying process, we must first accept the scientific principle that oil and water do not naturally mix. Quite literally, they find each other's presence repulsive. A good illustration of this aversion is homemade oil and vinegar salad dressing.When you shake or beat your salad dressing, you do more than disperse the oil throughout the vinegar: you also break down the oil into droplets minute enough to remain temporarily suspended in the vinegar (which from now on we will call water, because that tart condiment is in effect mainly water). The second you stop agitating the dressing, the oil droplets start to combine into units too large to be suspended in the water, and thus slither their way upward, separating from the water in the process. The oil rises to the top and the water sinks because oil has a lower specific density than water. If you want a stable emulsion, you need an emulsifying agent which prevents the oil droplets from combining into larger units. Emulsifying agents occur naturally in many animal substances including egg yolks and milk. An emulsifying agent helps to keep the oil particles from combining in three basic ways. First, the agent coats the oil, serving as a physical barrier between the droplets. Second, it reduces the water's surface tension, which, in turn, reduces the water's ability to repulse oil. Third, the agent gives the surfaces of the oil droplets identical electrical charges; since like charges repel each other the droplets repel each other.

2019年12月大学英语六级阅读晨读美文：Oil and Water.doc

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