top rafter

例句：

1. 1. The top rafter of the house is rotting away due to age.
   这栋房子的顶梁因为年久失修而开始腐烂。
2. 2.The builders were using a new type of top rafter to reinforce the structure.
   建筑工人正在使用一种新型的顶梁来加固结构。
3. 3.The top rafter supports the weight of the roof and also acts as a safety measure.
   顶梁支撑着屋顶的重量，同时也是一种安全措施。