Question

Очень нужно! Задание на фото! ​

Answer 1

An ordinary pen is wrote by you. Its color is changed if mistake is made by you. Mistake is found by you easily and the homework is done without any problems. A lot of tests were made by scientists with the "clever" pen. The mistakes are saw by the pen. But the "clever"pens aren't sold by us in the shop. They is sold by us only in the spei department in our office.

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