【正确答案】正确答案： Volcanoes A volcano is an opening in a planet's surface or crust, / which allows lava, ash and gases to escape from the place below the surface. / It is dramatic evidence of the powerful forces at work inside the Earth. / Volcanoes are generally found where plates are moving apart or coming together. / Erupting volcanoes can pose many hazards. / And the most deadly volcanoes are usually those tall and conical ones / built up by many layers of eruptive materials. / They can destroy entire cities and kill large numbers of people. / Nevertheless, volcanoes also add nutritious substances to soils, / creating perfect conditions for many crops. /