A：A dormant volcano is one which is said to be likely to erupt in the future, or which has erupted within recorded history.
B：An active volcano is one which is in the process of erupting.
C：An extinct volcano is one which is unlikely to erupt again.
D：The eruption can either be sudden, or an eruption can be slow and constant, with a cloud of gases, ashes and lava being emitted more or less all the time.
E：There are commonly thought to be three types of volcanoes: extinct, dormant and active.
F：Volcanoes are places where magma, which is a kind of melted rock below the earth ' s surface, pushes through to the surface of the earth in an eruption, or explosion.