假冒产品制造商经常使用劣质材料，这些假冒产品往往是禁不住一些机构单独的质量认证检测，如美国保险商实验所(UL)的认证。
Manufacturers of counterfeit products often use inferior materials and these "knock-offs" consistently fail independent certification testing from organizations such as Underwriters Laboratories (UL).
假冒产品制造商经常使用劣质材料，这些假冒产品往往是禁不住一些机构单独的质量认证检测，如美国保险商实验所(UL)的认证。
Manufacturers of counterfeit products often use inferior materials and these "knock-offs" consistently fail independent certification testing from organizations such as Underwriters Laboratories (UL).
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