Answer the questions（根据以下内容回答问题）
It was Saturday again. Grace and Karen disliked Saturdays. That was another thing the twins had in common. They shared the same clothes and tied their hair in the same manner. In fact, it was hard for their classmates and teachers to tell them apart sometimes.
Unlike their classmates, they had to get up early at seven every Saturday to prepare for their lessons. Grace had to attend the art lesson and Karen had to attend her ballet lesson. "How I wish I could do something different today," said the twins with one voice. All at once, an idea came to Grace and Karen at the same time. "How would you like to be me for a day?" they asked each other. It seemed like a wonderful plan to them. After giving each other a description of their own friends, Grace put on Karen's ballet dress while Karen put Grace's brushes and paints into her bag. Then they left for their classes.
When the art lesson started, Karen was lost. Unlike Grace, Karen was poor at drawing. When the art lesson finally ended, Karen didn't dare to hand in her work.
Meanwhile, Grace was struggling in the ballet class as well. As she had no idea about the dance steps, she had to follow her classmates blindly. As a result, she kept knocking into them. Their ballet teacher became impatient with her, "Karen, you should remember the basic steps. You can't rely on copying what others are doing."
When Karen and Grace got home, they were tired out. They decided that they would never try to be someone else they were not. It seemed that the grass was not always greener on the other side.
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