Only the first one is a complete sentence: "Someone who is persistent continues doing something ." Main clause: Someone continues doing something Subordinate clause: who is persistent Your second and third versions are grammatically correct, but they’re not full sentences, as they lack a main clause. In other words, "someone" needs to have a verb of its own (the subject of the verb in these sentence fragments is the relative pronoun "who").

The first sentence is the most correct! "Persistent" is an adjective, so it describes "someone" who "continues doing something". I would say that in terms of meaning, I would probably define "persistent" as a little bit more complex than just someone who "continues doing something"- to make the meaning more complete, one could change it to "Someone who is persistent continues doing something, even when they get frustrated or don't want to do it" :) 2. "Someone who persistently continues doing something" is not technically wrong, but it is an incomplete sentence. When you add the -ly to "persistent", it becomes an adverb describing someone's actions, not the person themself. I could be absolutely wrong but this translator is extremely accurate, so I think this might be translated as "Ktoś, kto uporczywie coś robi..." which is not in itself a full sentence. uparty = persistent uporczywie = persistentLY 3. The third one has the same problems with being an incomplete phrase, and is also grammatically wrong- should be "someone who is persistently continuing TO DO something" (instead of "doing"). Due to the fact that "is" is already there, "doing" should be changed to "to do" (the "infinitive" form). That's usually the rule for sentences with more than one verb: She wants TO WALK the dog. He screamed TO ANGER his mother. Good luck! :)

i think it suppose "someone who is persistent doing something" because the word 'doing' already represent present continuous tense, so if you put the word 'continuing' it show repetition. correct me if I'm wrong