1. Adverts are made by advertising agencies. - Passive - are made.
2. Advertising agencies make adverts. - Active - make.
3.Pop singers sometimes refer to products in their songs. - Active - refer.
4. Products are sometimes referred to by pop artists in their songs. - Passive - are referred.
5. Companies sell products on the Internet. - Active - sell.
6. Products are sold on the internet. - Passive - are sold.
7. Their songs are played on the radio. - Passive - are played.
8. DJs play their songs on the radio. - Active - play.