听力原文：JB: After 30 years of steady decline, Earth's ozone layer is thinner but seems to

be stable. A ban on ozone-depleting CFCs is largely responsible. Computer modeling gives reason to hope for an almost full recovery of Earth's ozone layer within 60 years. But this sort of modeling is difficult -- and its predictions aren't iron-clad.

DB: And some models show the ozone layer could face a new threat -- from global warming. Drew Shindell, an atmospheric scientist at NASA's Goddard Institute for Space Studies in New York City, talked with us about his computer models of climate.

Which of the following statements is true of "Earth's Ozone Layer"？

A．Earth's ozone layer is thinner and doesn't seem to be stable.

B．The largely responsible part lies on a ban on ozone-depleting CFCs, when the Earth's ozone layer seems to be stable.

C．Earth's ozone layer will realize its' full recovery within 60 years.

D．Some computer models show the ozone layer far from the threat of global warming.