英语六级考试备考阅读美文(七)
<p> <span word="Oil">Oil</span> <span word="and">and</span> <span word="Water">Water</span></p><p> <span word="To">To</span> <span word="understand">understand</span> <span word="the">the</span> <span word="emulsifying">emulsifying</span> <span word="process">process</span>, <span word="we">we</span> <span word="must">must</span> <span word="first">first</span> <span word="accept">accept</span> <span word="the">the</span> <span word="scientific">scientific</span> <span word="principle">principle</span> <span word="that">that</span> <span word="oil">oil</span> <span word="and">and</span> <span word="water">water</span> <span word="do">do</span> <span word="not">not</span> <span word="naturally">naturally</span> <span word="mix">mix</span>. <span word="Quite">Quite</span> <span word="literally">literally</span>, <span word="they">they</span> <span word="find">find</span> <span word="each">each</span> <span word="others">others</span> <span word="presence">presence</span> <span word="repulsive">repulsive</span>. <span word="A">A</span> <span word="good">good</span> <span word="illustration">illustration</span> <span word="of">of</span> <span word="this">this</span> <span word="aversion">aversion</span> <span word="is">is</span> <span word="homemade">homemade</span> <span word="oil">oil</span> <span word="and">and</span> <span word="vinegar">vinegar</span> <span word="salad">salad</span> <span word="dressing">dressing</span>.<span word="When">When</span> <span word="you">you</span> <span word="shake">shake</span> <span word="or">or</span> <span word="beat">beat</span> <span word="your">your</span> <span word="salad">salad</span> <span word="dressing">dressing</span>, <span word="you">you</span> <span word="do">do</span> <span word="more">more</span> <span word="than">than</span> <span word="disperse">disperse</span> <span word="the">the</span> <span word="oil">oil</span> <span word="throughout">throughout</span> <span word="the">the</span> <span word="vinegar">vinegar</span>: <span word="you">you</span> <span word="also">also</span> <span word="break">break</span> <span word="down">down</span> <span word="the">the</span> <span word="oil">oil</span> <span word="into">into</span> <span word="droplets">droplets</span> <span word="minute">minute</span> <span word="enough">enough</span> <span word="to">to</span> <span word="remain">remain</span> <span word="temporarily">temporarily</span> <span word="suspended">suspended</span> <span word="in">in</span> <span word="the">the</span> <span word="vinegar">vinegar</span> . <span word="The">The</span> <span word="second">second</span> <span word="you">you</span> <span word="stop">stop</span> <span word="agitating">agitating</span> <span word="the">the</span> <span word="dressing">dressing</span>, <span word="the">the</span> <span word="oil">oil</span> <span word="droplets">droplets</span> <span word="start">start</span> <span word="to">to</span> <span word="combine">combine</span> <span word="into">into</span> <span word="units">units</span> <span word="too">too</span> <span word="large">large</span> <span word="to">to</span> <span word="be">be</span> <span word="suspended">suspended</span> <span word="in">in</span> <span word="the">the</span> <span word="water">water</span>, <span word="and">and</span> <span word="thus">thus</span> <span word="slither">slither</span> <span word="their">their</span> <span word="way">way</span> <span word="upward">upward</span>, <span word="separating">separating</span> <span word="from">from</span> <span word="the">the</span> <span word="water">water</span> <span word="in">in</span> <span word="the">the</span> <span word="process">process</span>. <span word="The">The</span> <span word="oil">oil</span> <span word="rises">rises</span> <span word="to">to</span> <span word="the">the</span> <span word="top">top</span> <span word="and">and</span> <span word="the">the</span> <span word="water">water</span> <span word="sinks">sinks</span> <span word="because">because</span> <span word="oil">oil</span> <span word="has">has</span> <span word="a">a</span> <span word="lower">lower</span> <span word="specific">specific</span> <span word="density">density</span> <span word="than">than</span> <span word="water">water</span>. <span word="If">If</span> <span word="you">you</span> <span word="want">want</span> <span word="a">a</span> <span word="stable">stable</span> <span word="emulsion">emulsion</span>, <span word="you">you</span> <span word="need">need</span> <span word="an">an</span> <span word="emulsifying">emulsifying</span> <span word="agent">agent</span> <span word="which">which</span> <span word="prevents">prevents</span> <span word="the">the</span> <span word="oil">oil</span> <span word="droplets">droplets</span> <span word="from">from</span> <span word="combining">combining</span> <span word="into">into</span> <span word="larger">larger</span> <span word="units">units</span>. <span word="Emulsifying">Emulsifying</span> <span word="agents">agents</span> <span word="occur">occur</span> <span word="naturally">naturally</span> <span word="in">in</span> <span word="many">many</span> <span word="animal">animal</span> <span word="substances">substances</span> <span word="including">including</span> <span word="egg">egg</span> <span word="yolks">yolks</span> <span word="and">and</span> <span word="milk">milk</span>. <span word="An">An</span> <span word="emulsifying">emulsifying</span> <span word="agent">agent</span> <span word="helps">helps</span> <span word="to">to</span> <span word="keep">keep</span> <span word="the">the</span> <span word="oil">oil</span> <span word="particles">particles</span> <span word="from">from</span> <span word="combining">combining</span> <span word="in">in</span> <span word="three">three</span> <span word="basic">basic</span> <span word="ways">ways</span>. <span word="First">First</span>, <span word="the">the</span> <span word="agent">agent</span> <span word="coats">coats</span> <span word="the">the</span> <span word="oil">oil</span>, <span word="serving">serving</span> <span word="as">as</span> <span word="a">a</span> <span word="physical">physical</span> <span word="barrier">barrier</span> <span word="between">between</span> <span word="the">the</span> <span word="droplets">droplets</span>. <span word="Second">Second</span>, <span word="it">it</span> <span word="reduces">reduces</span> <span word="the">the</span> <span word="waters">waters</span> <span word="surface">surface</span> <span word="tension">tension</span>, <span word="which">which</span>, <span word="in">in</span> <span word="turn">turn</span>, <span word="reduces">reduces</span> <span word="the">the</span> <span word="waters">waters</span> <span word="ability">ability</span> <span word="to">to</span> <span word="repulse">repulse</span> <span word="oil">oil</span>. <span word="Third">Third</span>, <span word="the">the</span> <span word="agent">agent</span> <span word="gives">gives</span> <span word="the">the</span> <span word="surfaces">surfaces</span> <span word="of">of</span> <span word="the">the</span> <span word="oil">oil</span> <span word="droplets">droplets</span> <span word="identical">identical</span> <span word="electrical">electrical</span> <span word="charges">charges</span>; <span word="since">since</span> <span word="like">like</span> <span word="charges">charges</span> <span word="repel">repel</span> <span word="each">each</span> <span word="other">other</span> <span word="the">the</span> <span word="droplets">droplets</span> <span word="repel">repel</span> <span word="each">each</span> <span word="other">other</span>.</p>
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