allofwhich不能用作非限制性定语从句吗?Thirteenhundredmedicalprofessors,allofwhichhavebeentrainedtotreatdrugdependency,attendedtheannualconventionsponsoredbytheSocietrytoPreventDrugAbuse.当中把allofwhich改

　　allofwhich不能用作非限制性定语从句吗?

　　Thirteenhundredmedicalprofessors,allofwhichhavebeentrainedtotreatdrugdependency,attendedtheannualconventionsponsoredbytheSocietrytoPreventDrugAbuse.当中把allofwhich改为allofwhom的原因是什么?

　　Thereareovernaturalelements,someofwhichareveryfamiliar.本句中someofwhich用法应该是正确的