A:speaking? understand
B:spoken; understand
C:speaking; understood
D:spoken; understood
—I didn't go to bed ________ 12 o'clock last night because there was too much homework.
实验室配制一定溶质质量分数的稀硫酸并用其除铁锈,部分操作如图所示,其中正确的是( )
下列物质的性质属于物理性质的是( )
①向社会主义过渡方式的改变 ②所有制结构的改变
③经济管理体制的改变 ④分配制度的改变