问题补充：
, the car could not be started.
A. Having lost the key
B. He lost the key
C. The key was missed
D. The key lost
答案：
A. Having lost the key
B. He lost the key
C. The key was missed
(答案→)D. The key lost
解析：考查独立主格。the car could not be started.是完整的句子，前后没有连词，排除B和C，而选A项 Having lost the key，后面的主语不能是the car，所以选D ，The key lost为独立主格结构。
