SAT语法题扫盲,求分析TODO和DOING的区别,
AmongtheaearliesttelescopesbwereGalileantelescopes,modeledafterthesimpleinstrumentscbuiltbyGalileo,thefirstpersondhavingusedtelescopestostudythestarsandplanets.eNoerror
分析一下D选项为什么错