So fast it is difficult for us to imagine its speed.
A. does light travel that
B. light travels that
C. as light travels that
D. with light travels
网友回答
(答案→)A. does light travel that
B. light travels that
C. as light travels that
D. with light travels
解析：so—that，句式当so+adj./adv.置于句首，句子要倒装。