阅读理解
An 80-year-old man was sitting on the sofa in his house along with his 45-year-old highly educated son. Suddenly a crow (乌鸦) landed on their window.
The father asked his son, “What is this?”
The son replied, “It is a crow.”
After a few minutes, the father asked his son for the second time, “What is this?”
The son said, “Father, I told you just now. It's a crow. ”
After a little while, the father again asked his son the same question for the third time, “What is this?”
This time, the son said to his father in a low and cold tone, “It's a crow, a crow.”
After a moment, the father again asked his son for the fourth time, “What is this?”
This time the son shouted at his father, “Why do you keep asking me the same question again and again? I have told you already, ‘IT IS A CROW'. Are you not able to understand this?”
A minute later the father went to his room and came back with a diary, which he had kept since his son was born. On opening a page, he asked his son to read that page. The following words were written in it.
Today my little son aged three was sitting with me on the sofa when a crow suddenly landed on the window edge. My son asked me 23 times what it was, and I replied him 23 times that it was a crow. I hugged him lovingly each time he asked me the same question. I didn't at all feet angry, but instead felt affection for my son.
So...
If your parents reach old age, do not look at them as a burden, but speak to them gently, and be kind to them. Be considerate to your parents.
中,圆
的方程为
,若直线
上至少存在一点,使得以该点为圆心,1为半径的圆与圆
的取值范围是（ ）