Barack Obama delivered a speech to 500 local youths during his visit to China many ofwer

问题补充：

Barack Obama delivered a speech to 500 local youths during his visit to China, many ofwere from Fudan University and Tongji University.

A. them

B. whom

C. which

D. those

答案：

A. them

(答案→)B. whom

C. which

D. those

解析：考查非限制性定语从句。先行词是500 local youth，指人用who/whom/that，排除C；根据逗号判断，是非限制性定语从句，有and的话，是并列分句，A、D不能引导定语从句，排除A、D；故选B。