— Could I have an interview with Mr Green now, please?
— Sorry, he _________ a meeting. You'd better wait a minute.
A:has
B:had
C:is having
D:was having
同学们提出了以下保护金属资源的措施,其中不正确的是( )
如图是配制100g溶质质量分数为5%的氯化钠溶液的操作过程.以下说法错误的是( )