An electric can opener works by getting a gear to spin, which spins a can to cut its top off. Electricity flows into the can opener through a wire and is transformed into mechanical energy options:

by an electric generator.

by a laser beam

by an electric battery

by an electric motor

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answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation:

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.