1 Complete the text with the past passive form of the verbs in brackets. Use by when necessary. Modern text messages, or SMS, I were invented (invent) in 1992. Early messages? (not write) on a mobile phone, they could only be sent from a computer to a phone. In 1993, the first mobile- to-mobile SMS service 3 (introduce) in Sweden. It wasn't immediately popular, but by 2011, an average of 19.9 billion texts 4 (send) people every day. In the same year, SMS messages 5 (replace) chat apps, such as WhatsApp. They (use) to send 19 billion texts a day. Experts think this number is going to double in the next two years.