От чего зависит продолжительность существования экосистем?почему жизнь дубравы более продолжительна,чем жизнь смешанного леса?

Помогите

Open the brackets

1. Last Friday I (to see) him in the park. He (to jog).

2. Ann (to look) tired in the morning. She ( to prepare) for the conference the whole night. 3. They (to meet) last month. They (not to see) each other for a long time.

4. Their family (to visit) same doctor for years.

5. It is rather wet. It (to rain) for last 3 days.

6. It is midnight. Clive (to study) hard for seven hours.

7. When Tony (to arrive) at Tina's place yesterday, she ( to read) a detective story which she (to buy) some days before.

8. Two men (to walk) throught the forest for five hours before they ( to see) the house of the forest guard. They (to be) hungry because they (not to eat) anything since last evening.

Помогите выразить h из формулы l =  корень из (2*R*h)

в треугольнике abc высота  cd делит  угол c на два угла, причем угол acd = 25 градусов  , угол bcd =  40 градусов

высоты данного треугольника пересекаются в точке о найдите угол boc

Имеются ли различия по числу хромосом между маткой и рабочими особями медоносной пчелы?