to produce produced to buy bought bought
15. Put the verbs in brackets into the Present Perfect Tense.
1. Computers .. (to help) the children to learn much more quickly.
2. The introduction in recent years of digital radios .. (to allow) us to enjoy much better sound quality.
3. The Internet .. (to make) it possible to enjoy radio and television from around the world on our PCs.
4. Computer technology .. (to become) a rapidly growing industry.
5. People .. (to invent) a lot of computers.
6. A human .. (to tell) the machine what to do.
7. Manufacturers .. (to develop) entertainment systems which include television, radio, DVD recorder / player, and computer.
16. Complete the sentence and underline the correct word in bold.
1. Nearly one hundred and fifty years ago / recently there were no such things as computers.
2. Hundreds of computers are already / just in daily use.
3. In some Japanese elementary schools there are already / still lessons on using computers.
4. I have been working here since / for 2010.
5. They still / already haven't employed a new supervisor.
6. Don't forget to send a mail to him. I've just / since mailed him.
7. He has already / yet designed the computer.