CREATE TABLE table_name_13 (inf_stem VARCHAR, subj_pres VARCHAR, plur_pret VARCHAR)

What is the infinitive stem that is associated with a subjunctive present of a and a plural preterite of uo?
SELECT inf_stem FROM table_name_13 WHERE subj_pres = "a" AND plur_pret = "uo"
SELECT "inf_stem" FROM "table_name_13" WHERE "a" = "subj_pres" AND "plur_pret" = "uo"