show the name of the wines with scores higher than 90.
select name from wine where score > 90
among them, which are made from white grapes?
select t2.name from grapes as t1 join wine as t2 on t1.grape = t2.grape where t1.color = "White" and t2.score > 90
what different grape varieties were they made from?
select distinct t1.grape from grapes as t1 join wine as t2 on t1.grape = t2.grape where t1.color = "White" and t2.score > 90