19. ‘Harry Potter’ is a series of seven fantasy novels written by J. K. Rowling. The main storyline ______ around Harry’s quest to overcome the evil dark wizard Lord Voldemort. Since the release of the first novel ‘Harry Potter and the Philosopher’s Stone’, the books ______ immense popularity and commercial success worldwide.

The correct forms are: revolves and have gained.

The main storyline revolves around Harry’s quest to overcome the evil dark wizard Lord Voldemort. Since the release of the first novel, the books have gained immense popularity and commercial success worldwide.

Ответ: revolves; have gained.