simple beam

例句：

1. 1. The engineer designed a simple beam to support the roof.
   工程师设计了一根简单的梁来支撑屋顶。
2. 2.The construction of this bridge required the use of simple beams.
   这座桥的建设需要使用简单的梁。
3. 3.The beam was made of wood and had a length of about three meters.
   这根梁是用木头做的，长度大约三米。