TOEFL Listening: ETS-TOEFL听力机经 - 46KARF_6YVU36P14P$

According to the professor, what feature of propeller turbines makes them an undesirable choice for generating power for the university? A. The turbines are costly to maintain. B. Each turbine requires the installation of a special foundation. C. The turbines cannot be placed close together. D. Propeller turbines do not last as long as vertical axis wind turbines.