сколько процентов суши занимают равнины от площади суши?

упростите выражение 3(в-1)в 2 степени+8b  

  (2+а)(2-ф)(4-а   а в 2 степени)-а в 4 степени

  (x+2   2 во 2 степени) умножить (x-2    2 во 2 степени)(4-a a во 2 степени) -x в 4 степени+16

 2с(8с-3)-(4с+1) это (4с+1)   в 2 степени  

Перечислите основные вехи политической биографии М.М. Сперанского в 1801-1812 г. Чем вы объясните успех его карьеры ?

учёные которые изобрели треугольник

Упражнение № 2

Напишите предложения, используя PerfectProgressive (совершенное длительное) и  forили sinceпо данному образцу.

Example: It is raining now. It began raining two hours ago.

                It has been raining for two hours.

1. Kevin is studying. He began studying three hours ago.

He __________________________________________for three hours.

2. I’m learning Spanish. I started learning Spanish in December.

I ____________________________________________since December.

3. Ann is looking for a job. She began looking two months ago.

She __________________________________________for two months.

4. Mary is working in London. She started working there on 18 January.

She__________________________________________since 18 January.

5. George plays golf. He started playing five years ago.

He___________________________________________ for five years.

6. Tom writes short stories. He began writing last year.

He ___________________________________________ since last year.

7. Miss Stone dances ballet. She began dancing when she was four.

She ___________________________________________since she was four.