Finally, I can use all these sentences: 1. Some of the apples I've eaten recently are green. 2. Some of the apples I've eaten recently were green. 3. Some of the apples I've eaten recently have been green. 1 is not right because they have been eaten and no longer exist! 2 and 3 are ok.

First you have to understand the difference: HAVE is used for plural possessive or personal possessive. This is used when you have something or had something, the focus is more on WHAT you have, had (if past tense) or what you did. Ex. They HAVE food. I HAVE seen that movie. Think of it this way, "I have been playing soccer" the reply to that can be "What? really? oh me too!" In that sentence, you're more interested with WHAT they did or have done (which is play soccer). WERE is used for plural past tense. This is used when you had something or did something, the focus is more on WHEN you had it, or did it Ex. They WERE in Korea. We WERE at my friend's house. Think of it this way, "They were playing soccer" the reply to that can be "When? when did they play? I wanted to play too!" In that sentence, you're more interested with WHEN they did it (which is playing soccer) 1) Some of the films I've seen recently have been very violent. ----->WRONG, but can be corrected: Some of the films I've seen recently HAD been very violent. (had is the plural of have, which is singular, and filmS is supposed to be plural). 2) Some of the films I've seen recently were very violent. ----->CORRECT, this is right because since you since you were specifying WHEN you saw the films, which was recently.

I would say, Some of the films I've seen reсently are very violent.

Finally, I can use all these sentences: 1. Some of the apples I've eaten recently are green. 2. Some of the apples I've eaten recently were green. 3. Some of the apples I've eaten recently have been green.