It is hard for me to imagine what I would be doing today if I________in love，at the age of seven，with the Melinda Cox Library in my hometown.

A．wouldn’t have fallen

B．had not fallen

C．should fall

D．were to fall

在物体的顶部高出周围地面或附近建筑物的顶部（）以上的场合，必须在其中间层加设障碍物灯。

A、10m

B、15m

C、40m

D、45m