Shopping by television will never take ____ place of shopping in stores, as many experts say, because

many people find shopping at a store ____ great enjoyment.[ ]

A./; a    

B. the; a    

C. a ; the    

D. a; /

氨制冷系统中使用的安全阀、旁通阀、压力表在安装前，必须经相关计量部门进行校验、铅封。