题目

      Thomas and Louis Border founded Border Book Store in 1971. They were brothers in their 20s at the time and opened a small used book shop in Ann Arbor, Michigan. They managed to work out and inventory management system, servicing independent booksellers, and by 1988 their business had grown to include four stores.      They employed Robert DiRomualdo to run the business and then sold Borders to Kmart in 1990. Since then, Kmart has been selling the company to the public, and Robert DiRomualo is at present the CEO. Borders now operates over 225 Borders superstores, with one in Sin在溶解固体物质与过滤操作中，玻璃棒的作用分别是 ①搅拌溶液，加速其溶解 ②搅拌溶液，增大其溶解度 ③使液体沿玻璃棒缓缓流入 ④用玻璃捧起固定作用 [　　] A．①②B．②③ C．③④D．①③