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.​

Modern text messages, or SMS were invented in 1992. early messages weren’t written on a mobile phone, they could only be sent from a computer to a phone. in 1993, the first-to-mobile SMS service 3 were introduced in Sweden. it wasn’t immediately popular, but by 2021, an average of 19.9 billion texts 4 were sent by people every day. in the same year, SMS messages 5 were replaced chat apps, such as WhatsApp. they were used to send 19 billion texts a day. experts think this number is going to double in the next two years.