помогите пожалуйста

Используйте слова из скобках в множественом числе
1  business person are involved in the management of company 
2 my father builds bridges
3  Every year they spend a couple of months at the seaside
4  in our orchard we grow potatoes and tomatoes
5  this museum exhibits the 18th-century organs, pianos and grand piano
6  why do financial crises happen?
7  I want to read Shakespeare's plays, both tragedies and comedies
8 roofs on houses vary in geometry, method of ventilation and covering material
9 there are computer disks in those boxes
10 at the Geography lessons we study natural phenomenons