TOEFL Reading: ETS-TOEFL阅读机经 - 67P4G3ZKHWVA3WV9L$

Paragraph 3 indicates that all of the following are true of thermals EXCEPT: A. Air movement is more intense at their higher reaches. B. They can rise above cloud level. C. They usually become wider as they rise. D. They sometimes rise more than a kilometer from Earth's surface.