向（prep.） "at; to" 
  
    向 here means "to" in the sense of "facing or toward someone or something". It is usually employed only when the action is dynamic. 向 can be placed before or after the verb phrase when it is used as a preposition. 
                        
                       Subj.+向+ Obj. +VP 
                      Subj.+VP+向+Obj.
Examples:
1. 经理向客人问好。
The manager said hello to his guests.
2. 工人向厂长报告存在的问题。
The workers report the existing problems to the factory director.

Substitutive drills: