Please help write SQL queries for the following questions:

1. List all pairs of bikes that have the same condition. The result should contain three columns such that and have the same bike condition. A pair should appear only once in the output. (Tip: This is a self-join.)

2. List all participants id, first, and last name who have not a giveaway. Use an anti join.

3. List the participants who have not volunteered before August 15th, 2019 (Use NOT EXISTS).

4. List the course numbers, name, and capacity of courses without enrollments. Use a MINUS operator

5. List the bike name, bike brand, and the volunteer time required. Also indicate the time commitment level: 'High' if volunteer time required exceeds 30 hours, 'Middle' if volunteer time is between 20 and 30 (including 20 and 30), and 'Low' if volunteer time is below 20