Only when she reached her office she had left her key at home.
A. she realizes
B. does she realize
C. she realized
D. did she realize
网友回答
A. she realizes
B. does she realize
C. she realized
(答案→)D. did she realize
解析：考查only的倒装句。当only放在句首，且强调的是状语的时候，后面的主句使用部分倒装的形式。本题only放在了句首，后面强调的是时间状语when she reached her office，故后面的主句使用部分倒装的形式。故句中的reached，说明本句使用的是一般过去时，故D项正确。