He will move onto the next most popular topic soon.

The study of cells was an increasingly popular topic in this time period.

Finding comprehensive information on this popular topic can be tough.

They seem to be a popular topic of conversation these days.

They are the drums of war for most popular topics.

The environment is a popular topic these days and there are many special conservation groups all around the country.

Care work is becoming a popular topic for academic study and discussion.

Most popular topics are user's daily life and about computer games.

The weather has always been a popular topic of discussion in this country.

The series became a very popular topic on the internet.