Teacher: In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Passage: The group was occasionally diverted from strategic missions to carry out air support and interdiction missions. It supported Operation Overlord, the invasion of Normandy by attacking transportation targets, including bridges, along with airfields and strong points in France. On D Day, the squadron and the rest of the 446th Group led the first heavy bomber mission of the day. The 446th aided ground forces at Caen and Saint-Lo during July by hitting bridges, gun batteries, and enemy troops. During Operation Market Garden, the attempt to seize a bridgehead across the Rhine in the Netherlands, the 704th dropped supplies to allied troops near Nijmegen. It struck lines of communications during the Battle of the Bulge. During Operation Varsity in March 1945, it supplied ground and airborne troops near Wesel. The squadron flew its last combat mission on 25 April 1945 against Salzburg, Austria. The group had flown 273 missions and had lost 58 aircraft during the war,
. Link Information: Operation Market Garden was a failed World War II military operation fought in the Netherlands from 17 to 25 September 1944. Question: When did the operation during which the 704th dropped supplies to allied troops near Nijmegen begin?
Solution: from 17 to 25 September 1944
Reason: The passage describes the 704th's actions during Operation Market Garden, and the answer specifies when the operation happened.

Now, solve this instance: Passage: Born in Lichfield, Staffordshire, Leadbitter was a successful grasstrack racer before taking up speedway in 1966 at the training school at Long Eaton. After a single match for Glasgow Tigers in 1966 he rode in four matches for Long Eaton Archers in 1967. In 1968 he was signed by newly formed Leicester Lions, but only made one appearance for the team that season, spending most of it on loan to Middlesbrough Teessiders. In 1969 he progressed with Middlesbrough, averaging close to nine points per match, and had rode in four matches in the top division as a guest for Newcastle Diamonds. In 1970 he stayed with Middlesbrough as well as riding in several matches for his parent club Leicester, and was recalled to a full team place for the Lions in 1971. He competed in the Second Division Riders Championship in 1970, finishing in fifth place. At the end of the season he transferred to Wolverhampton Wolves where he spent four seasons, establishing himself as a solid scorer, although in 1975 his rides for Wolves were limited and he returned to Teesside in the National League where he averaged over nine points and recorded five full maximum and three paid maximum scores in 33 matches. After a second season back with Teesside in 1976 he moved on to Bristol Bulldogs in 1977, his final season before retiring.
Link Information: none Question: Has any of the teams Leadbitter rode for between 1966 and 1968 won a championship?
Student:
Answer: none