下半年大学英语六级考试语法及词汇精选（6）
<p> 情态动词</p><p> 这些无人称和数的变化的动词也是经常考查的内容，对于它们的掌握除了一般用法以外，一些特殊的用法一定要牢记。</p><p> <span word="l">l</span> 、 <span word="might">might</span> 不是 <span word="may">may</span> 的过去式而是表示一种很小的可能性。 <span word="might">might</span> 如果用完成式则表示过去发生的很小的可能性。如： <span word="You">You</span> <span word="might">might</span> <span word="have">have</span> <span word="told">told</span> <span word="me">me</span> <span word="that">that</span> .</p><p> 2 、作为情态动词 <span word="need">need</span> 和 <span word="dare">dare</span> 除在 <span word="whether">whether</span> 和 <span word="if">if</span> 引出的从句中以外，一般不能用于肯定句，只能用于否定句和疑问句，并且不采用助动词 <span word="do">do</span> ，但是作为实义动词 则需要 <span word="do">do</span>, 试比较</p><p> <span word="He">He</span> <span word="doesn">doesn</span><span word="t">t</span> <span word="need">need</span> / <span word="dare">dare</span> <span word="to">to</span> <span word="do">do</span> <span word="it">it</span> .</p><p> <span word="He">He</span> <span word="needn">needn</span><span word="t">t</span> / <span word="dare">dare</span> <span word="not">not</span> <span word="to">to</span> <span word="do">do</span> <span word="it">it</span> .</p><p> 3 、 <span word="used">used</span> <span word="to">to</span> 表示过去习惯的动作或者状态，即现在已经不存在了， <span word="be">be</span> <span word="used">used</span> <span word="to">to</span> <span word="doing">doing</span> 则表示习惯于某种状态。</p><p> 4 、 <span word="might">might</span> 和 <span word="as">as</span> <span word="well">well</span> 连用表示建议，口气比同样表示建议的 <span word="had">had</span> <span word="better">better</span> 要婉转一些，两种用法后面都要跟动词原型。</p><p> 5 、 <span word="ought">ought</span> <span word="to">to</span> ， <span word="should">should</span> <span word="be">be</span> ， <span word="must">must</span> <span word="be">be</span> / <span word="must">must</span> <span word="have">have</span> <span word="been">been</span> ， <span word="will">will</span> <span word="be">be</span> ，，用来表示论断、逻辑推理等。如： <span word="He">He</span> <span word="ought">ought</span> <span word="to">to</span> <span word="be">be</span> <span word="here">here</span> <span word="by">by</span> <span word="now">now</span> .再如：</p><p> <span word="Mary">Mary</span> <span word="isnt">isnt</span> <span word="here">here</span> <span word="now">now</span> .</p><p> <span word="left">left</span> <span word="by">by</span> <span word="the">the</span> <span word="back">back</span> <span word="door">door</span>?</p><p> <span word="A">A</span> . <span word="Must">Must</span> <span word="she">she</span> <span word="have">have</span> <span word="B">B</span> . <span word="Might">Might</span> <span word="she">she</span> <span word="have">have</span> <span word="C">C</span> . <span word="Had">Had</span> <span word="she">she</span> <span word="D">D</span> . <span word="Should">Should</span> <span word="she">she</span> <span word="have">have</span></p><p> 根据以上所讲的第一点， <span word="B">B</span> 选项表示过去发生的很小的可能性，前半句说玛丽不在这里了，后半句理应对于她去了哪里作一个推测，由于不确定，用的是问号，所以正确答案是 <span word="B">B</span> 。</p>
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