1.on the roof 在...顶上
Craig to fight on the roof of a moving train, the railway ministry said he persuaded the producers to modify the scene.
最初的剧本要求克雷格在一辆行驶中的列车车顶上搏斗，但据印度铁道部长称，他说服制片方对这一场景进行了修改。

2.on the trail 在小路上
On the trail to Goodnow Mountain, a yellow birch appears to be ingesting a boulder left behind by a glacier.
通往古德诺山的一条小径上，一株黄桦缠绕在一块冰川流动之后显现出来的鹅卵石上。

3.pace off 用步子量出
At fifteen-meter intervals they pace off precise quadrants, collecting surface artifacts and environmental data.
每隔15米他们用步子测出准确的象限，收集地面的物品和环境数据。