请问咋吧echarts单折线图变成双线呢

option = {
title: {
text: 'Distribution of Electricity',
subtext: 'Fake Data'
},
tooltip: {
trigger: 'axis',
axisPointer: {
type: 'cross'
}
},
toolbox: {
show: true,
feature: {
saveAsImage: {}
}
},
xAxis: {
type: 'category',
boundaryGap: false,
// prettier-ignore
data: ['00:00', '01:15', '02:30', '03:45', '05:00', '06:15', '07:30', '08:45', '10:00', '11:15', '12:30', '13:45', '15:00', '16:15', '17:30', '18:45', '20:00', '21:15', '22:30', '23:45']
},
yAxis: {
type: 'value',
axisLabel: {
formatter: '{value} W'
},
axisPointer: {
snap: true
}
},
visualMap: {
show: false,
dimension: 0,
pieces: [
{
lte: 6,
color: 'green'
},
{
gt: 6,
lte: 8,
color: 'red'
},
{
gt: 8,
lte: 14,
color: 'green'
},
{
gt: 14,
lte: 17,
color: 'red'
},
{
gt: 17,
color: 'green'
}
]
},
series: [
{
name: 'Electricity',
type: 'line',
smooth: true,
// prettier-ignore
data: [300, 280, 250, 260, 270, 300, 550, 500, 400, 390, 380, 390, 400, 500, 600, 750, 800, 700, 600, 400],
markArea: {
itemStyle: {
color: 'rgba(255, 173, 177, 0.4)'
},
data: [
[
{
name: 'Morning Peak',
xAxis: '07:30'
},
{
xAxis: '10:00'
}
],
[
{
name: 'Evening Peak',
xAxis: '17:30'
},
{
xAxis: '21:15'
}
]
]
}
}
]
};

series里再添一条数据

option = {
  title: {
    text: 'Distribution of Electricity',
    subtext: 'Fake Data'
  },
  tooltip: {
    trigger: 'axis',
    axisPointer: {
      type: 'cross'
    }
  },
  toolbox: {
    show: true,
    feature: {
      saveAsImage: {}
    }
  },
  xAxis: {
    type: 'category',
    boundaryGap: false,
    // prettier-ignore
    data: ['00:00', '01:15', '02:30', '03:45', '05:00', '06:15', '07:30', '08:45', '10:00', '11:15', '12:30', '13:45', '15:00', '16:15', '17:30', '18:45', '20:00', '21:15', '22:30', '23:45']
  },
  yAxis: {
    type: 'value',
    axisLabel: {
      formatter: '{value} W'
    },
    axisPointer: {
      snap: true
    }
  },
  visualMap: {
    show: false,
    dimension: 0,
    pieces: [
      {
        lte: 6,
        color: 'green'
      },
      {
        gt: 6,
        lte: 8,
        color: 'red'
      },
      {
        gt: 8,
        lte: 14,
        color: 'green'
      },
      {
        gt: 14,
        lte: 17,
        color: 'red'
      },
      {
        gt: 17,
        color: 'green'
      }
    ]
  },
  series: [
    {
      name: 'Electricity',
      type: 'line',
      smooth: true,
      // prettier-ignore
      data: [300, 280, 250, 260, 270, 300, 550, 500, 400, 390, 380, 390, 400, 500, 600, 750, 800, 700, 600, 400],
      markArea: {
        itemStyle: {
          color: 'rgba(255, 173, 177, 0.4)'
        },
        data: [
          [
            {
              name: 'Morning Peak',
              xAxis: '07:30'
            },
            {
              xAxis: '10:00'
            }
          ],
          [
            {
              name: 'Evening Peak',
              xAxis: '17:30'
            },
            {
              xAxis: '21:15'
            }
          ]
        ]
      }
    },
    {
      name: 'demo',
      type: 'line',
      smooth: true,
      data: [123, 155, 212, 123, 212, 312, 352, 311, 123, 212, 211, 231, 321, 341, 453, 542, 651, 521, 341, 321],
      markArea: {
        itemStyle: {
          color: 'rgba(255, 173, 177, 0.4)'
        },
      }
    }
  ]
};