6 Complete with the correct form of the verb. (5 points)

Решение:

In the 1970s, people started (start) using mobile phones for the first time. It wasn't (not be) easy to use these phones because they were very big. You didn't see (not see) many people using these mobile phones. In the early 1990s, a company made (make) the first smartphone. After this time, more and more people got a mobile phone. Today, there are (be) billions of mobile phones in the world!

Ответ: started; wasn't; didn't see; made; are.