Write questions and answers in the passive voice, as in the example. a in France b Sir Arthur Conan Doyle c Charles Dickens

2 e
3 a
4 b
5 d

2 When was the Leaning Tower of Pisa completed? The Leaning Tower of Pisa was completed in the 14th century.
3 Where was the Eiffel Tower constructed? The Eiffel Tower was constructed in France.
4 Who were the Sherlock Holmes stories written by? The Sherlock Holmes stories were written by Sir Arthur Conan Doyle.
5 Where were the 2004 Summer Olympics held? The 2004 Summer Olympics were held in Athens, Greece.

Меди 20%цинка 80%20кг - 80%20%=80%/420кг/4=5кг5кг=20% -> масса меди = 5кг