Thanks so much. Now I have the test for determining whether a term is past tense or past participle. I just have to bear in mind that in some cases I might have to decide which term sounds 'less' strange, accept the less strange sounding one, and know that the less strange sounding one is the past participle. I accept what you say, but it seems to me that there is still a missing link somewhere. For example, something that would help the non-native English speaker who isn't necessarily the best judge of what sounds 'less strange' versus what doesn't. Oh well.
