把住关口to guard a pass

掌握原则to ensure

比喻按照标准严格检查to make stringent checks

• 由于建筑面积计算复杂，即便有政府背景的测绘机构“把关”，老百姓还是不放心。

  Even though the mapping agency, which has a government background, is making stringent checks, the people are still worried because the calculation of the construction area is complicated.

• 各级国土资源主管部门要从用地报批、审查到批后实施各个环节强化把关和监管。

  Departments of all levels in charge of national land and resources must strengthen stringent checks and supervisory procedures in all phases, from land use approval and examination to implementation after approval.