center to center distance between main girder

例句：

1. 1. Thecar was parked at the center ofthe square.
   汽车停在广场的中心。
2. 2. The teacher askedus to stand in the center of theroom.
   老师让我们站在教室的中央。
3. 3. The marathonrunners lined up in the centerof the track.
   马拉松跑者在赛道中央排队。