The following text is for questions 20 to 22

    Once, there lived a horse in a stable. Adjacent to it, a bufallo lived in a pen. Both the animals belonged to a farmer who treated them fairly. However, the horse thought that it was more important because it worked harder than the buffalo. It went out with its master almost every day and had to carry burdens on its back. On the other hand, the farmer used the bufallo only for plowing the rice field. When the farmer didn’t use it, it remained in its pen. 

    “Hey, buffalo. I don’t know why our master keeps you. You are less important. You only work when our master needs you. Look at me! I work for our master every day,” said the horse. 

    “Who said that I am useless? I help our master plow his land and it’s not an easy task,” replied the buffalo. 

    “Ha ha ha____it’s not hard work. Any animal can do that, including me. You see, I”ll help our master plow the land,” boasted the horse. 

    Then, the horse told the farmer its intention. Feeling unsure, the farmer refused the idea. However, the horse insisted and the farmer accepted. 

    On a very hot afternoon, the farmer tied the horse to his plow. Then, he asked the horse to start plowing. The horse began the task enthusiastically. It wanted to show that it could plow better than the buffalo. However, it could not do it for too long. It was very tired and fell down. It finally realized that it was hard work. 

    “Now, you see that you cannot do everything. You should not underestimate me.  We have our own duties,” said the buffalo calmly. 

From the story, we can learn that____