运行代码: xx2161<-getSymbols("^SSEC",from="2015-01-01",to="2015-08-01",auto.assign = FALSE) 显示如下 Warning: ^SSEC download failed; trying again. Error in getSymbols.yahoo(Symbols = "^SSEC", env = , verbose = FALSE, : Unable to import “^SSEC”. 缺少参数"conn",也没有缺省值