name the office holder with predecessor as alfred milner and office in president of the board of trade ?
SELECT DISTINCT var_uri where brack_open var_uri dbp_predecessor dbr_Alfred_Milner,_1st_Viscount_Milner sep_dot var_uri dbp_office dbr_President_of_the_Board_of_Trade sep_dot var_uri a dbo_OfficeHolder brack_close