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When the downward sloping surface CD has a larger fabrication angle than the critical angle c , no supporting structures are required .
 concept or principle: surface; material: CD; manufacturing process: fabrication; engineering feature: critical angle; material: c
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 concept or principle: surface; material: CD; manufacturing process: fabrication; engineering feature: critical angle; material: c