求助，K线数据收盘价获取失败

function onTick() { exchange.SetContractType(“v000”); var records = _C(exchange.GetRecords);

var last_records = records[records.length-2];//上一根K线数
var last_Close = last_records[Close];//上一根K线数
Log(last_Close)

} 回测结果是这样 main:24:35 - ReferenceError: Close is not defined 这是啥情况？