Поясніть чому в деяких тканинах рослин переважають відмерлі клітини?

Правильно употребить глаголы в Past Simple, Past countinuous, Past Perfect
1. Kate ( to go) to the airport with her parents and her brother Nick. While they (to wait) at the airport, Nick (to remember) that he (to have) something important to tell Kate. Her friend (to phone) just as they (to leave) to ask at what time Kates flight (to leave). Previously Kates friend (to think) that she wouldnt be all to get to the airport in time but she (to turn) up while Kate (to say) goodbye to herr parents. she finally (to go) through passport control and everybody (to wake) goodbye.
2. It (to be) the day of this English exam. He (to wake) up and (to look) at this alarm clock. He (to see) that it (to stop) raining during the night. He (to realise) he would be late for his exam. He (to be) an hour late and exam already (to begin). When he (to sit) at the table, he (to find) that he (to leave) his pen at home. He ( to ask) his friend his friend to give him a pen. Despite everything (to go) wrong he (to pass) him exam.

Площадь равнобедренного прямоугольного треугольника равна 8. Найти длину окружности, описанной около этого треугольника