1 Complete the text with the past passive form of the verbs in brackets. Use by when necessary. Modern text messages, or SMS, 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 (send) people every day. In the same year, SMS messages (replace) chat apps, such as WhatsApp. They 6 (use) to send 19 billion texts a day. Experts think this number is going to double in the next two years.