读短文，根据短文内容，选择正确答案。
One evening Nick's mother said to Nick, “Look at your sports shoes. How dirty they are! You must clean them.”
“Oh, Mother, but I cleaned them only yesterday,” said the boy.
They are dirty now. You must clean them again.”
“I don't want to clean them today. Even if (即使) I clean them today, they will be dirty again tomorrow.” Nick's mother said, “All right.”
The next evening Nick came back from school. He was very hungry.
“Mother, give me something to eat, please,” he said.
“You had your breakfast in the morning, Nick, and you had lunch at school,” his mother said.
“I'm hungry again,” cried the boy.
“Oh, hungry? But if (如果) I give you something to eat today, you will be hungry tomorrow.”