根据概念,(3的相反数)+(3)=0,则3的相反数是-3.
故选A.
The two friends ______on the Internet for three hours, and they would go on till the next morning.
A.have been chatting
B.had been chatting
C.were chatting
D.had chatted
如图是硝酸钾的溶解度曲线图,某同学在20℃时进行了如下实验,得到相应的溶液①~⑤,下列说法正确的是( )
A.保持温度不变,若在④中加入4.5KNO3固体可得到饱和溶液
B.②③⑤中溶质的质量分数相等
C.①③④均为不饱和溶液
D.④→⑤可析出53.9gKNO3晶体