The clusters early of the genus Homo were generally distinguished by regular use of stone tools and by a huntung and gathering economy.
答案是(A)
雖然答案很明顯, 但我想請問economy這個字, 何時為可數, 何時用不可數呢? 因為我一直以為economy是不可數的, 這次因為這題查了字典, 才發現它也可作可數名詞, 但裡面並沒有講解用法上的區分
Thanks