Wear a mask that is rated N90 or above .
戴上N90或标准更高的口罩。
Because of producing age , many of management software of N90 runing under the DOS system can 't adapt to the need of the development of corporation during recent years .
但受产品生产年代的制约，N90上运行的许多管理软件运行在DOS环境下，已不能适应今天企业发展的需要。
n90