楼房下水道堵塞现象极常见，其疏通方法很多。这里我推荐一种易为初中学生理解的“气压差法”。市面上出售的一种疏通下水道的工具：橡皮碗，其原理与它类似，但一般当竖直段筒身较长时就难以形成较大的气压差，因而只能疏通堵塞不严重的下水道。 当堵塞较严重并且下水道堵塞B Building blockage is extremely common sewer, which dredge a lot of ways. Here I recommend a “pressure difference method” that is easy for junior high school students to understand. A commercially available sewer cleaning tool: rubber bowl, and its principle is similar to it, but generally when the vertical section of the cylinder body longer it is difficult to form a larger pressure difference, which can only clear the blockage is not serious sewer. When the blockage is more serious and the sewer blockages B