1. When it has been decided where we are going to drill, we put up at the surface an oil derrick.
    当钻孔地点决定后, 我们就在那块地面上坚起一个井架.

2. When it has been decided where we are going to drill, we put up at the surface an oil derrick.
    当确定钻孔地点后，我们就在那里竖起一个井架。