TOEFL Reading: ETS-TOEFL阅读机经 - 54VTQPT5WW1O0EP9L$

Which TWO statements below about thermal chimneys would the biologists discussed in paragraph 3 regard as likely true To receive credit, you must select TWO answers. A. They cover only a small area. B. They sometimes contain dust devils. C. They usually spin very quickly. D. They usually end in a fluffy cloud.