A:2
B:-2
C:1
D:-1
92,93,88,76,105,90,71,103,92,91
—Thank you, Mr. Zhang. We'll try our best.
往硝酸铜、硝酸银和硝酸亚铁的混合溶液中缓慢连续加入质量为m的锌粉,溶液中析出固体的质量与参加反应的锌粉质量关系如图所示,下列说法中正确的是( )
A: What can you ____?
B: I can see two ____.
A: What ____ ____ they?
B: They are ____ and ____. (黑色和黄色)