译文修改:关于Hearing protection? “engineering controls are not always practical or do not effectively reduce noise to acceptable levels”. engineering controls: 好像应该指在工程设计上所采取的控制措施; are not always practical :指工程设计上所采取的控制措施不总是可行的; do not effectively reduce noise to acceptable levels:不会有效的吧噪音降低到可以接受的范围内 acceptable level是否就是合理的标准呢?查看更多