请问下 but 是连词,是否和and 的用法相似,and用法形式特别平行, but连接内容形式是不是也要很平行,
gwd 2 里的 Q 27,的正确选项,
Pennsylvania was once apredominantly grain-producing state, but competition in the mid-nineteenthcentury from large western farms gradually caused the state’ s farmers to turnto livestock raising.