4700
Placing the entire structure under vacuum evacuates most of the air from these cavities through a reservoir of liquid metal that covers a single inlet .
 concept or principle: structure; material: liquid metal; machine or equipment: inlet
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: structure, liquid metal, inlet 
Answer:
 concept or principle: structure; material: liquid metal; machine or equipment: inlet