抛物线y=-x²+bx+c的部分图象如图所示，若y≥0，则x的取值范围是（   ）

    Vandna loved sports and did well in her lessons at her high school in California. When a headache disturbed the 15-year-old girl's walk to class, she 1 it.

    “It was 2.” she thought, “Just a headache—harmless”

But when walking to her next class, she was 3 and collapsed to the floor. 4 she could hear other talking, she couldn't speak. She was 5 to the hospital in an ambulance. Tests indicated Vandna had a stroke affecting the right side of her brain, thus affecting the 6 side of her body.

    What was worse, the stroke caused her brain to began to swell, and she needed operation to 7 the pressure the swelling was putting 8 her brain. The doctors 9part of her skull（头骨）to make room for the swelling. 10 the swelling went down（消退）, her skull was placed back again.

    While the doctors predicted that she would never live a normal life, Vandna 11 improved. She was in a rehab center（康复中心）for about 3 months and began to realize how 12 her daily life might be. She had to wear a brace（支架）on her left leg to support her 13. Her left arm 14 lightly, and she often became tired. Though 15 on a campus wasn't easy, she finished high school and 16 a degree in speech therapy at University of Redlands.

    After the stroke, Vandna became 17 with the American Heart Association. She shared her 18 at public events and urged others to stay 19. She said if you 20 a tough time, remember tough times don't last, but tough people do.