list the common prime minister of the robert gascoyne-cecil and david eccles ?
SELECT DISTINCT var_uri where brack_open dbr_Robert_Gascoyne-Cecil,_5th_Marquess_of_Salisbury dbo_primeMinister var_uri sep_dot dbr_David_Eccles,_1st_Viscount_Eccles dbo_primeMinister var_uri brack_close