Among the molecules between TR004 to TR010, how many of them has single bonds?
single bond refers to bond_type = '-'; molecules between TR004 to TR010 refers molecule_id BETWEEN 'TR004' and 'TR010';
SELECT COUNT(DISTINCT T.molecule_id) FROM bond AS T WHERE T.molecule_id BETWEEN 'TR004' AND 'TR010' AND T.bond_type = '-'