4006
Cheng admits that if he utilized extraneous processes , such as exposing the pieces to wood smoke for a long time , he could get the colors closer to those of the actual artifacts , but then he would be losing something else at the same time .
 Cheng
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: date, organization, person, geographical social political, national religious political, facility, cardinal, location, work of art, law, event, product, ordinal, percent, time, quantity, money, language 
Text: {0} 
Answer:
 Cheng