Theory:

     I swallowed the pips and put some of the peel in my mouth.

     ‘Don’t eat it!’ said the voice. ‘There isn’t time. Swallow it! Be quick! Swallow it!’

     I took a small knife from my pocket and cut the oranges into large chunks. I swallowed the pieces of oranges one after the other.

     There were still three oranges on the table when I heard Pongo outside. I stopped. My stomach was nearly full.

     ‘Be quick! Swallow them!’ said the voice in my head.

     I was lucky. Pongo and the other policeman had seen some carts at the dock gate. They went and talked to the drivers. This gave me a few more minutes.

     I must swallow all the oranges, I thought. Only three left!

     I swallowed the first one, and then the second one.

     Suddenly the door began to open. I went through a great deal of struggle and finally managed to finish off the last piece of the last orange. Pongo and the other policeman walked in.

     ‘This is the thief.’ Pongo said. ‘I caught him with his pockets full of oranges.’
 
     Then Pongo looked at the table and at first, he could not figure out what had happened. ‘Where are the oranges?’

     ‘I can smell them,’ said the other policeman.
 
     I said nothing.

     Pongo looked everywhere for the oranges. He looked in my pockets. He looked in my apron. But he didn’t find one orange.

     Finally, Pongo understood what had happened. But it was very difficult to believe.

     ‘Seventeen oranges!’, he said.

     ‘Seventeen big oranges! How did you eat them all?’

     I said nothing. Pongo was not able to send me to prison. There was no evidence.

     Pongo became angry and shouted at me. But I didn’t say a word. In the end, he had to let me go. I told Clem Jones about the seventeen oranges.

     ‘Pongo locked you in that cabin for half an hour,’ said Clem. ‘He had no right to do that.’

     Perhaps Clem was right. I don’t know. I didn’t have time to think about it. I had eaten seventeen large oranges -peels, pips and all. I felt very sick for a week and those oranges kept working away in my stomach.
Explanation:
  
The boy swallowed the seeds. When he wanted to chew the orange peels, his inner voice told him to swallow it quickly as he had no time for chewing. He took a small knife from his pocket and cut the oranges into big pieces and swallowed one by one. There were still three oranges left on the table when the boy could hear Pongo. The boy's stomach was full, but his inner voice asked him to swallow the three oranges left on the table.
 
desk_3_lemons.svg
 
Luckily Pongo and his colleague saw some carts at the gate of the dock, and they went to them to talk to the drivers. That gave the boy some more time to swallow the three oranges.

He swallowed the first one and then the second orange. The door began to open suddenly. Finally, the boy finished off the last orange with a lot of struggle. Pongo and the other policeman entered the cabin. Pongo showed the boy to the other policeman and said that he was the thief and that Pongo caught him with oranges in his pocket. But when Pongo looked at the table, he could not understand anything. He could not believe his eyes when he realized what might have happened. The other policeman said that he could smell oranges. Pongo tried to search for the oranges in the narrators pocket and apron, but he could not find even one orange. Finally, Pongo understood what might have happened to the oranges.

Pongo exclaimed, "Seventeen oranges!" That too, the oranges were so big, how could the boy eat them all. Pongo had no evidence, so he could not send the boy to the jail. Pongo became enraged and shouted at the boy, but the boy did not utter a word. Finally, he had to let the boy go. The boy narrated his story of seventeen oranges to Clem Jones. Clem was worried at the fact that Pongo locked the boy in the cabin for half an hour and he has no right to do that. Clem was right, but the boy had no time to think of these things when he was in the cabin. The boy had eaten seventeen big oranges with the peel and the seeds. He was not well for a few weeks as those oranges in the stomach were too much for him.
 
Meanings of difficult words:
 
Numbers
Word
Meanings
1.
Pips Seed.
2.
Dock An enclosed area of water in a port for the loading, unloading, ships.
3.
ChunksSolid piece of something.
4.
Figure out Determine.
Reference:
State Council of Educational Research and Training (2019). Term-2 English Standard-9. Seventeen Oranges - Bill Naughtan(pp. 93-97). Published by the Tamil Nadu Textbook and Educational Services Corporation.