下列类别的物质中一定不含氢元素的是( )
A.酸
B.碱
C.酸式盐
D.碱性氧化物
答案:D
如图所示的电路,电源电压不变,闭合开关S1、S2,两灯都发光,当把开关S2断开时,灯泡L1的亮度及电流表示数变化的情况是( )
A.L1变亮,电流表示数变小
B.L1亮度不变,电流表示数变小
C.L1变亮,电流表示数不变
D.L1亮度不变,电流表示数不变
—How do you deal with their objections to our plan?
—I think we can safely ____ them since our plan is made on a scientific basis.
A.approve
B.dismiss
C.distribute
D.disgust