Theory:

   I returned to my senses only after the loss of all the wealth. I decided to sail for the Persian Gulf with some goods. Our group sailed from one country to another, selling the goods. One day, when we were on board, we saw a beautiful small green island. Just to have some fun, we all got down on that green patch. We were hungry and so we decided to cook some food there. As soon as we lit the fire for cooking, we got a jerk. The island was trembling. It was no island. It was the back of a huge animal, which got disturbed when the fire was lit on his back. We were terrified when we realized this. Everyone jumped into the sea to save his life. Most of them boarded the ship. But a few were not so fortunate. Before they could climb up, the captain started the ship hurriedly leaving behind a few sailors who were still struggling in the sea for their life. I was one among those strugglers. Fortunately, I caught hold of a big piece of wood floating nearby and held on to it.
Explanation:
 
Sindbad realised his mistakes after losing everything he owned. The sailor decided to earn a lot of money. So he started his journey with some goods to the Gulf of Persia. His crew members travelled from one country to another to sell goods.
 
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Sindbad and the crew members
 
On a fine day, when Sindbad and his crew members were sailing on the sea, they noticed an island in the distance. The island seemed to be very beautiful. It was a small green island with plenty of trees and bushes over it. The green patches over the island made them feel very excited. The sailor and his crew members decided to have some fun and entertainment over the island.
 
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Beautiful green island
 
After a while, Sindbad and his crew members felt very hungry, and they decided to cook some food. When they started to light a fire, Sindbad and his crew noticed that the ground began to tremble.
 
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Sindbad and the crew members lit a fire
 
Sindbad and his crew members got scared, and they did not know what was happening. They saw the back of a giant animal. Finally, they realised that they were not standing on an island; Sindbad and his crew members were standing on a water animal. It was believed that the water animal was a big Whale. The trees and bushes over the animal made them feel like an island. The animal became disturbed when they lit the fire on it. To save their own lives, Sindbad and the crew members ran away and jumped into the water.
 
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Huge water animal (Whale)
 
Fortunately, many of the crew members boarded the ship; sadly, a few missed it. When a few crew members tried to climb up, the captain started the ship hurriedly. The fear did not allow the captain to think about who was not on the ship. Unknowingly, the captain of the ship left them in the sea. Sindbad was one of the passengers who failed to board the ship. After struggling for a long time, Sindbad, the sailor, was surprised to see a large piece of wood floating nearby. Immediately, he grabbed the piece of wood using his hands. The piece of wood saved his life.
 
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Sindbad grabbed the piece of wood
 
Meanings of the difficult words:
 
S.No
Words
Meanings
1
Persian GulfA sea in Western Asia
2
CrewA group of people who work on and operate a ship or aircraft
3
IslandA piece of land surrounded by water
4
TremblingShaking of ground 
5
GrabbedGrasp or seize suddenly and roughly
6
PassengersA traveller on a public or private conveyance other than the driver, pilot, or crew
7
EntertainmentAn event, performance, or activity designed to entertain others
8
HungryHaving a strong desire or craving for food
9
Terrified Cause to feel extreme fear
10
JerkA quick, sharp, sudden movement
11
FortunateFavoured by or involving good luck; lucky
12
StrugglersA person who struggles with difficulties or with great effort
Reference:
State Council of Educational Research and Training (2019). Term-1 English Standard-7. Sindbad-My First Voyage (pp. 97-104). Published by the Tamil Nadu Textbook and Educational Services Corporation.