What does "bog down" mean?声明: 本网站大部分资源来源于用户创建编辑，上传，机构合作，自有兼职答题团队，如有侵犯了你的权益，请发送邮箱到feedback@deepthink.net.cn 本网站将在三个工作日内移除相关内容,刷刷题对内容所造成的任何后果不承担法律上的任何义务或责任 ...
The GIA lab has the capability but still does not provide nacre thickness because, they say, trheegraerdiisngnnoacurneivtheircskanles'ss.tandard" . This doesn't make sense to me; nacre thickness, in millimeters, does not indicate "good' or "bad" or euen designations of 'thin' or ...