You can only use surprising. It’s an adjective. The thing was surprising. The thing wasn’t surprised. That implies something surprised the thing. The cat was surprised by the dog etc

I've seen this question before--it can be a little confusing. An easy way to think of it is. SURPRISING = did the action. SURPRISED = recieved/experienced the action. Imagine you are walking down the street and a tiger runs in front of you. The action of the tiger running in front of you would be a SURPRISING thing. You would be SURPRISED. One logical consequence is that something must be a living being (i.e. not a thing) to be SURPRISED. Hope that helps.

This follows a rule for many adjective pairings in English: Often, if the adjective is formed from a verb we can add two different endings. -ed describes an emotion, and is used for people. -ing describes a situation, thing (or sometimes a person) that makes you feel the above emotion Examples Verb: to surprise -ed = I am surprisED that you came... You told me you weren't coming. -ing = He has a girlfriend? That's surprisING! Verb: to bore -ed = I get so borED talking to him. -ing = He always tells these long, borING stories. I think he is a borING person. Verb: to interest -ed = I've been interestED in pottery since I was a kid. -ing = I don't like watching football – it's not interestING.