Because sales in the Asia-Pacific Region have been disappinting for the last three years,we are moving to revamp out entire marketing approach in the regions. 請問disappointing 可以換成disappointed嗎?

Disappointing and disappointed are both adjectives, but they are used differently. (Similar to boring/bored, surprising/surprised, etc.) ***** Disappointed describes how a person feels. I am disappointed means that I *feel* disappointed. (It is from the passive voice: to be disappointed by something.) ***** Disappointing describes something that makes people feel disappointed. X is disappointing means that X *makes people feel* disappointed. ***** So: The sales are disappointing (to us) = We are disappointed by the sales. The sales are disappointed is not correct because the sales are not a person, so they can’t feel disappointed.