A:x1=0,x2=-2
B:x1=1,x2=2
C:x1=1,x2=-2
D:x1=0,x2=2
一块表面被氧化的铝片质量为15.6g,将其放入烧杯中,加入213g稀硫酸,恰好完全反应,反应后,称得烧杯中的溶液质量为228g,求:(提示:Al2O3+3H2SO4═Al2(SO4)3+3H2O 2Al+3H2SO4═Al2(SO4)3+3H2↑)
—Who taught Zhu Zhiwen to sing? —________! He learned singing by himself.
The students were singing happily_________ I passed the school hall.
教师是一个古老的职业,时代进步推进着师生关系的变化。在现代教育中,师生关系是一种人格平等,互相尊重的关系。这种新型的师生关系建立的基础是( )