with sentences as ( 
    select 'Sentence 1: There once was a poor boy who spent his days going door-to-door selling newspapers to pay for school. One day, as he was walking his route, he started feeling low and weak.The poor boy was starving, so he decided to ask for food when he came to the next door. Sentence 2: The poor boy asked for food but was denied every time, until he reached the door of a girl. He asked for a glass of water,but seeing his poor state, the girl came back with a glass of milk. The boy asked how much he owed her for the milk, but she refused payment.Sentence 3: Years later, the girl, who was now a grown woman, fell sick. She went from doctor to doctor, but no one was able to cure her.Finally, she went to the best doctor in town.Sentence 4: The doctor spent months treating her until she was finally cured. Despite her happiness, she was afraid she couldn’t afford to pay the bill. But, when the hospital handed her the bill, it read, ‘Paid in full, with a glass of milk.’'
    s from dual 
) 
select listagg(sentence, ' ') within group (order by lvl) 
from ( 
    select substr(s, instr(s, 'Sentence', 1, level), 50) sentence, level lvl
    from sentences 
    connect by level <= regexp_count(s, 'Sentence') 
)