Complete the sentences with the correct form of the present perfect or past simple. 1) success of the yablochkov candle in 1878 ) all expectations – mass media all around the world ) about the outstanding invention of a russian scientist. 2) electricity ) a subject of scientific interest since at least the seventeenth century. 3) in the 19th century the subject of electrical engineering with tools of modern research techniques, ) to intensify. 4) electricity is used with telecommunications, and indeed the electrical telegraph, demonstrated in 1837 by cooke and wheatstone ) one of its earliest applications. 6) electricity is the best source of energy. while there are other sources of energy none of them ) the stage where they can be used to provide the power to help modern life go. 6) the processes used to produce electricity using the sun’s energy historically ) more expensive than using conventional fossil fuels. 7) in 2015, less than 1% of the nation’s electricity ) by solar power. 8) in 1827 georg simon ohm (quantify) the relation between electrical current and potential difference between conductors – leading to ohm’s law.
2 has been
3 started
4 was
6 has reached
6 was
7 was supplied
8 quantified