中南半岛湄公河流经的国家最多，在下列哪一国家注入南海（     ）

China plans to digitize the management of its grain industry by 2020 to improve food security, ________ grain transportation between provinces and the amount of imported grain have been high in recent years.

到超市调查一种牛奶的价格和一天的销售量，算一算这种牛奶每天能卖多少钱?

下列物质属于纯净物的是（　　）

选择与图片相符的一项。

A. sports meet       B. singing contest       C. Easter     D. April Fool's Day   E. school trip