Swallow teaches you to distinguish between true and false "Tongli Cement"

Cement quality is related to engineering safety, do not let inferior materials "penetrate", do not let the problem project "latent". In this issue, we use the protagonist of the TV series- "Swallow" to help you distinguish between true and false " Tongli Cement ", and use a few simple and practical "secret books" to teach you how to quickly pull out the "Li Gui" in "Tongli Cement"!

Keep your eyes open and avoid the pit with the swallows!