Need guidance on essay!

Hello everybody! I had written an essay but my english teacher said it was not well written, vocabulary and did not end good.

I hope someone could read my essay and teach me where to add in expressions and more vocabulary... and ... maybe could teach me some vocabs to add in to the essay to improve ^^ ! I would love to improve my vocabulary and the usage of good phrases !
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An occasion when you had to put up with someone who was very difficult to get along. ( The storyline was taken from somewhere)

“Liz, get ready! They are coming at one in the afternoon!” Mum hurried me. I purposely chose my dress slowly. My wonderful aunt and that imbecilic baboon were coming to visit us from . That simpleton would be none other than my extremely irksome cousin.
He is fourteen and yet he acted as though he was six years old. Just listening to his voice alone would make me want to puke.

At exactly one in the afternoon, my perfect aunt and that ‘baboon’ arrived.

“Lizzy! My dear girl, how nice to see you!” My aunt ruffled my hair and passed me a nicely wrapped present. What an aunt! Yon He, my cousin, was standing beside her and smiling sweetly to my mum. Once my mother turned her back, Yon stuck out his tongue at me. How could I spend a whole day with him! I wanted to faint; I needed to find an excuse to get away from him – for a day, at least.

“Oh, look who’s calling,” I increased the decibel count of my voice. The phone on my hand wasn’t even ringing. “Hi, Jasme! Oh, today… Yes… I am free, no problem. See you there!” I acted.

“Stop pretending Liz.” Amazingly, my mother had seen through my act. “Would you like to bring Yon to the nearby mall?” She asked.

“Nope, not really,” I replied quickly. All the time, Yon was watching me with his beady eyes. It was not that I was mean or anything, but he was very difficult to get along with.

“Aunty, I really hope Liz can bring me to tour around,” he paused for a second. “I really, really hope I can have some time with my lovely cousin.”

He was telling a pack of lies!

For an hour, I tried persuading mother that I had homework to do but she was not convinced. Reluctantly, I bought ‘baboon’ out for a walk.

We were passing by a fruit stall while on the way to the mall. I was telling him that Singapore was no different from and suggested that he need not come visit that often. Suddenly, the uncle tending the fruit stall interrupted me.

“Hey, boy! That will be two dollars!” I managed to stop myself from crushing Yon into powder. While I was talking to him just now, he was busy pinching a mango. After I painfully dug out a two-dollar note and handed to the uncle, Yon actually had the nerve to pass a comment.

“What? Two dollars for that soft thing? ’s mangoes are so much better and cheaper at only one dollar each!” He said to me after I had paid the badly damaged mango. I forced my anger down.

Next, we passed by a shop selling branded bags. “Look at that Converse bag! I bought one at home for only twenty-five dollars! It’s selling at forty dollars!” I willed him to shut up, but failed. I could have bit his head off but I knew that the mummy’s pet was going to complain.

“Liz, I want that teddy bear!” Yon whined loudly while pointing to the soft toy on the shelf of a toy shop in the mall. His whine was so loud that I was so sure everyone in the mall could hear him.

“Grow up, Yon, you’re no longer a kid!” I snapped at him. There’s no way I am going to use my own money on him again. I saw the direction of his eyes drifted to me. His eyes were getting moist.

‘Darn, he’s going to cry.’ I thought.

“Mummy will buy me anything I want in ! You must buy that for me! I want it and I must have it!” He was stamping his foot on the floor, each step pounded like thunder.

Suddenly, a hot tiny bubble of anger burst inside me. The mercury shot through the thermometer. I needed to teach this brat who the boss was.

“Look over there!” I pointed, “It’s your favourite Manchester United soccer T-shirt!” I knew he was a huge fan of Manchester United. This ought to do it! As he was blabbering on about how cheap the shirt was in , I tiptoed away – my whole body howled with merriment.

After an hour of silence at home, Yon was back – brought back by the police. You should have seen Yon’s face. It was violently red with fear. He was sobbing so much that he could not breathe. I enjoyed watching his face. I even compliment myself for doing such a magnificent job even though I had gotten a hard scolding from my mother after that. That should teach Yon a lesson! I laughed secretly. The scolding I got was worth it. It was amazing to let him be lost in the mall!
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