求助SAT改错题一道

题目

求助SAT改错题一道
Prior to the election of Henry Cisneros as mayor of San Antonio in 1981,no major city in the US had had a mayor from Mexican descent.
错在from Mexican descent
既然descent意思是下坡；血统；遗传...我就没太看懂这道题了.如果descent错了,错在哪了?应该改为什么呢?

答案

"Prior to the election of Henry Cisneros as mayor of San Antonio in 1981,no major city in the US had had a mayor [ from ] Mexican descent." =介系词错"Prior to the election of Henry Cisneros as mayor o...