under-grade wood

例句：

1. 1.The product is under-grade, which means it doesn't meet the standard requirements.
   这个产品是低于标准的，这意味着它没有达到标准要求。
2. 2. The company has been under-graded by the government for its poor environmental performance.
   该公司因环境表现不佳而受到政府的降级评价。
3. 3.The under-grading of the product indicates that it needs improvement in quality and safety.
   产品的降级表明其需要在质量和安全方面进行改进。