1.When using an automatic level and rod to conduct differential leveling for construction grade control of a concrete wall, the first necessary step following set up of the level is to:
2.A technical difficulty encountered in construction is that drill bits used to make holes for bloting concrete panels togather do not last long. suggest two creative ways to solve or avoid the problem.
3.If a line is known to have a true azimuth of 143° 07’ and the magnetic declination is 12° 6’ W, the magnetic bearing observed would be ?
4.Gate AB is 4m wide into the paper and opens to let fresh water out when the ocean tide is dropping. The hinge at A is 0.50m above the freshwater level. At what ocean level h will the gate first open?