【题目】So fast ________ that it is difficult for us to imagine its speed.
A. light travels B. light has travelled
C. does light travel D. travels light
在线课程【答案】C
【解析】考查倒装结构。句意：光传播得如此快以至于我们很难想象它的速度。在so... that...结构中，若将so+adj. / adv. 置于句首，则其后的主句要用部分倒装。部分倒装是将助动词提前到主语前面，故选C。