So absorbed in the research that she didn’t hear someone knocking at the door.A. she didB

问题补充：

So absorbed in the research that she didn’t hear someone knocking at the door.

A. she did

B. did she

C. she was

D. was she

答案：

A. she did

B. did she

C. she was

(答案→)D. was she

解析：句意：--她是如此专注于研究以至于他没有听到有人敲门。这里使用了so…that…句型，so+adj/adv.如果放在句首，句子用部分倒装，因为词组be absorbed in专注于，所以将was提前，所以选D。