3502
Gas turbine blades , turbine shafts and centrifugal compressor impellers are often damaged by erosion and/or corrosion .
 machine or equipment: Gas turbine; concept or principle: corrosion
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: Gas turbine, corrosion 
Answer:
 machine or equipment: Gas turbine; concept or principle: corrosion