Table: giro_1968
Columns: date
course
distance
type
winner

Question: Name the date which has type of plain stage
SQL: SELECT "date" FROM giro_1968 WHERE "type" = 'plain stage'

Question: Name the distance for Course of vittorio veneto to marina romea
SQL: SELECT "distance" FROM giro_1968 WHERE "course" = 'vittorio veneto to marina romea'