STATA问题，怎么都没有

Thepanel data set File3.dta (MathsScore) contains the following data:

District:        educational district
Year:                        year
Math4:        % of 4th year students with satisfactory grades in maths
Math7:        % of 7th year students with satisfactory grades in maths
Expp:                        Expenditure per pupil
CPI:                        Price index
Enrol:        Number of students enrolled
Lunch:        % of pupils receiving free school meals
Drop:                        High school drop-out rate %
这些是已知数据的描写

附件就是下面这个了，不过因为论坛不允许dta文件，所以请下载后改成.dta
希望能获得正确算出此结果的详细指令，从头到尾

gen lrealexpp=log(expp/ cpi)

gen lenrol=log(enrol)

reg  math4  lrealexpp lenrol  lunch drop

reg  math7  lrealexpp lenrol  lunch drop