Поставить в разные формы глагольного имени: я вчера купил щенка (p.s.) (positive,negative,qvestion) мой сын читал книгу в это время(p.c.) (positive,negative,qvestion) ученики написали тест к этому времени(p.c.) (positive,negative,qvestion)

I bought a puppy yesterday
I didn't buy a puppy yesterday
Did you buy a puppy yesterday?

The pupils had written the test by this time
The pupils had not written the test by this time
Had the pupils written the test by this time?