Database: toxicology
Question: What are the bonds that have phosphorus and nitrogen as their atom elements?
SQL: SELECT T2.bond_id FROM atom AS T1 INNER JOIN connected AS T2 ON T1.atom_id = T2.atom_id WHERE T2.bond_id IN ( SELECT T3.bond_id FROM connected AS T3 INNER JOIN atom AS T4 ON T3.atom_id = T4.atom_id WHERE T4.element = 'p' ) AND T1.element = 'n'