both … and

When the correlative conjunction both … and is used, the material appearing after and should correspond in structure to the material following both.

• Incorrect: Ann enjoyed camping both on the mountains and prairies. [phrase + noun]
• Correct: Ann enjoyed camping both on the mountains and on the prairies. [both phrases]
• Incorrect: Nenad liked both to cycle and jog. [to-infinitive + bare infinitive]
• Correct: Nenad liked both to cycle and to jog. [both to-infinitives]