求助！！
不晓得为什么每次使用foreach循环语句时都会显示invalid name的error

foreach i in trust deceive{
sort year
twoway connected 'i'_p 'i'_o year,xline(1958,lp(dash_dot)lw(0.5)lc(black))m(oh diamond)msize(1 1)lw(0.4 0.4)note("Data source: CGSS(2010,2012,2013,2015)")legend(ring(0)pos(5)cols(1))
graph export 'i'ratio_year.png,replace
}


就是想把重复的作图工作通过循环语句来体现，可是总是出错==