脚手架内的作业层应畅通，并搭设不少于（）处与主体建筑内相衔接的通道。

题目解析：脚手架是建筑施工中的一种临时性结构，用于支撑工人、材料和设备等，以便在建筑物上方进行施工和维护。在搭建脚手架时，作业层的畅通性至关重要，因为它直接关系到工人的安全。此外，为了方便工人和材料的运输，还需要搭设通道与主体建筑内相衔接。根据题目所述，应搭设不少于2处通道。因此，正确答案是C。 参考翻译：The working layer inside the scaffold should be unobstructed and equipped with not less than () channels connected to the main building. A.5 B.4 C.2 Answer: C. 解析：The scaffold is a temporary structure used in building construction to support workers, materials, and equipment for construction and maintenance above the building. When building a scaffold, it is crucial to ensure that the working layer is unobstructed, as it directly affects worker safety. In addition, to facilitate the transportation of workers and materials, channels should be set up to connect the scaffold to the main building. According to the question, not less than 2 channels should be set up. Therefore, the correct answer is C.