Witnesses in Nantong and Suzhou are not universal because the sampling rules in each region are different. The sampling certificate should be in the local quality monitoring station (quality supervision station), that is, the local laboratory. The specific examination time can be inquired online, and it should be rolling study at any time.

Supervision witness is a post in the supervision industry. Generally, the administrative department of construction at or above the prefecture level shall have a unified examination, and a supervision witness certificate shall be issued after passing the examination. This certificate generally does not accept applications and evaluations.