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A man was mending a street lamp when he saw a pretty young woman and three children get into a car which was in the garden of a house near him. He saw that the car had a flat tyre, and tried to warn the woman, but it was too late—she was already driving the car out of the garden, and into the busy street. When she had got there, she stopped the car at the side of the street, got out and looked at the flat tyre. The children stayed in the car. Very soon another car stopped, and the driver offered to help her. The young woman accepted his offer, and the man changed the tyre for her.
When she had thanked him and he had gone, she drove the car back into the garden, got out with the children and went back to her work in the house –with clean hands.
(x∈-2，2)表示圆的一部分，直线y=k（x-2)+4是过定点（2、4)的直线系，当曲线与直线有两个公共点时，实数k的取值范围是( )