There are mainly two specifications of steel guardrail: W-Beam guardrail and Thrie-Beam guardrail, They are manufactured from Q235B or Q345B grade steel in 2.5-4mm base metal thickness as supplied by China Steel Limited.All products are hot dipped galvanized or powder coate...
C. for five years ago D. five years 查看完整题目与答案 Glass ionomer cements are composed of( ) A. zinc oxide powder and polycarboxylic B. zinc oxide powder and phosphoric acid liquid C. aluminosilicate powder and phosphoric acid liquid D. aluminosilicate powder and polycarboxylic liqu...