GRE Text Completion: Fundamental 24 Sets-GRE填空基础24套 - C8I2PXW106N5EP14!

That bison congregate in large herds suggests that they are (i)____________ animals, yet individually they appear (ii)____________, seemingly indifferent to their circumstances. A. fastidious B. tractable C. gregarious D. stolid E. ubiquitous F. skittish