Reason:

Adjacent arrangement of Party A and Party B: 2 * 6 * 5 * 4 * 3 * 2 =1440;

Arrangements for Party C to be adjacent to Party A and Party B on June 10: 2 * 5 * 4 * 3 * 2 = 240;

Arrangements of Party A and Party B on June 7th10: 2 * 5 * 4 * 3 * 2 = 240;

Party C will be in June 10, June 1, and Party D will be in June 10. The arrangement adjacent to Party A and Party B is 2 * 4 * 3 * 2 = 48;

So the feasible method:1440-2 * 240+48 =1008.

This explanation should be no problem.