The five points difference method is used to calculate the voltage distribution on the meridian surface of axial-symmetrical electrostatic lens.

采用五点差分法计算轴对称静电透镜子午面上电位分布，再从普遍轨迹方程求得的电子轨迹出发得到透镜焦点和球差。

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Among the 2-to-4-year-olds, the difference in IQ was five points; among the older kids, there was a 2.8-point gap.

其中2到4岁这一批里面，得分的差距是5分，而5到9岁的一批里面，差距是2.8分。

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Among the 2-to-4-year-olds, the difference in IQ was five points; among the older kids, there was a 2.8-point gap.

其中2到4岁这一批里面，得分的差距是5分，而5到9岁的一批里面，差距是2.8分。

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