Przepisz zdania w stronie biernej.

1 Companies make boxes out of cardboard because it’s a cheap material.
2 Builders won't use concrete as much in the future.
3 A company called Dupont developed nylon in the 1930s.
4 The builders have broken the glass window.
5 People will recycle plastic more in the future.
6 Someone discovered rubber many years ago in South America.
7 People burn wood to heat buildings.