The young lady was careful .
A. not repeating her mistake
B. not repeated her mistake
C. to not repeat her mistake
D. never to repeat her mistake
网友回答
A. not repeating her mistake
B. not repeated her mistake
C. to not repeat her mistake
(答案→)D. never to repeat her mistake
解析：这是短语be careful not to do sth.的搭配，故选D。