If by "CO" you mean object complement, you may want to check out this site: http://www-personal.umich.edu/~jlawl.../complmnt.html
EX: They told you to go home. object complement
Object Complement Test
=> Insert a form of the verb BE between the direct object and the phrase in question, and if the result makes sense then the phrase in question functions as an object complement. For example: You are to go home.