---Bad luck! I the sidewalk when an Audi cut in and knocked me down.
---You can never be too careful!
A. crossed
B. have crossed
C. was crossing
D. had been crossing
网友回答
A. crossed
B. have crossed
(答案→)C. was crossing
D. had been crossing
解析：句意：--这倒霉！我在过人行道时突然一辆奥迪插过来把我撞到了。--你越小心越好。这是be doing …when….这在做某事突然发生了某事。根据knocked，所以用过去进行时，故选C。