- My teacher caught me sleeoing in class and l had to.
- Its’ really big secret, OK? You must not tell anyone.
- l can not come to your party. Mum says I’m not allowed to.
- Do you have to wear a uniform to school.
- I’m not completely stupid, you know.You neednt explain everything to me!
The radio was invented at the beginning of the 20 th century.In the First World War radios were used to communicate with soldiers.Since the 1960s, many radio signals were sent into outer space, So far, no answers were received from other planets, but the messages were not understood.
The planet Mars will be explored during the next few years. Special robot vehicles will be brought to investigate the planet’s surface.