TOEFL Reading: ETS-TOEFL阅读机经 - EBW54DS355F64X73L$

Paragraph 2 implies that which of the following is a factor that contributes to the formation of thermals A. In some areas, characteristics of the ground cause it to heat more than surrounding areas. B. The sun heats the air, causing it to start to rise. C. Warm air continues to rise until the ground beneath it is cooled by colder air. D. Uneven heating of the air causes it to rotate as it rises.