高速公路上方的龙门架上安装了电子显示屏。

Electronic signs were installed on the ___gantry above the expressway.

工人们正在用龙门架上的起重机搬运钢材。

The workers are moving steel beams with the crane mounted on the ___gantry.

火箭发射前，巨大的门式起重机被移开。

The massive ___gantry was rolled away before the rocket launch.