If we try to think of the most important inventions in the 20th century, I think electricity may (is) the most important, in a way. It plays important part in the development(发展) of the modern world. It can affect (影响) everyone's life. When the electricity (go) off, we call it a power cut. Can you imagine what (we) life will be like (with) electricity? Almost everything (stop). Electrical appliances(电器) can't work; traffic lights are dead; many workers must stop (work), and so on. Electricity is so (importance), it is also limited(有限的). should we do? At least (至少), we mustn't waste electricity.