为什么这种语法在 METAFUN/METAPOST 下会输出错误?
鉴于此 MWE(在 ConTeXt 下编译) \starttext \startMPpage %variables u:=1mm ; numeric l[]; l[1]:=30 ; l[2]:=70 ; draw (0,0) -- (0,100u) ; %this does not work %fill unitsquare xscaled (l[2]-l[1])*u yscaled 100*u shifted (l[1]*u,0) withcolor red ; %this does fill unitsquare xscaled (l[2]*u-...