题目

—I wonder why Susan looks worried today. —I’m not sure，but she________a small accident driving here. A．could have       B．might have        C．might have had    D．must have had   答案： C   考查情态动词表推测。句意为“……但是，她开车来时或许出过小事故”。既然是I’m not sure“不确信”，应该用might来表达推测，后面给出的时间状语是driving here开车来时，所以用might have had。  

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