Нужно найти конструкции пасивного состояния! этих текстов:
the history of rubber balloons. the first rubber balloons were made by professor michael faraday in 1824 for use in his experiments with hydrogen at the royal institution in london. "the caoutchouc is ex- ceedingly elastic", he wrote in the quarterly journal of science the same year. "bags made of it have been expanded by having air forced into them, until the caoutchouc was quite transparent, and when expanded by hydro- gen they were so light as to form balloons with considerable ascending power." faraday made his balloons by cutting round two sheets of rubber laid together and pressing the edges together. toy balloons were introduced by a pioneer rubber manufacturer thomas hancock the following year in the form of a do-it-yourself kit consisting of a bottle of rubber solution and a condensing syringe.
1.The first Rubber baloons ¦were made¦ by Professor Michael Faraday...
2."Bags made of it ¦have been expanded¦ by having air...
3.Toy baloons ¦were introduced¦ by a pioneer rubber...
¦ - Выделила сам пассивный залог прощения за то, что не написала предложения полностью, думаю не смертельно)