把20g溶质质量分数为95%的酒精,稀释为溶质质量分数为50%的酒精,根据需加水的体积 (水的密度为1g/cm3),为了减少实验误差,最好选用量筒的量程为( )
A:10mL
B:50mL
C:20mL
D:100mL
— He has few friends to share his joy and sadness, _____ he?
— _________. It’s really bad for him to keep quiet all the time.
今年,我市将“加大黄标车淘汰和水污染控制力度”、“实施废热利用减少燃煤大气污染”、“加快推行绿色建筑”。这说明我市( )