List emails of people who paid more than 20 dollars from 9/10/2019 to 11/19/2019.
expense_date BETWEEN '2019-09-10' and '2019-11-19'; cost > 20
SELECT DISTINCT T1.email FROM member AS T1 INNER JOIN expense AS T2 ON T1.member_id = T2.link_to_member WHERE date(SUBSTR(T2.expense_date, 1, 10)) BETWEEN '2019-09-10' AND '2019-11-19' AND T2.cost > 20