实验室能用右图装置制取气体,并能实现“随开随用,随关随停”。下列实验能选用该装置的是
A:二氧化锰粉末与过氧化氢溶液制取氧气
B:块状石灰石与稀盐酸制取二氧化碳
C:锌粉与稀硫酸制取氢气
D:碳酸钠和稀盐酸制取二氧化碳
Jerry won first prize in the speech competition. His parents are proud of his______.
To ______ something to happen means to believe that it will happen.
图甲是通过灯泡L的电流跟其两端电压关系的图象.现将L与阻值为10Ω的电阻R连入图乙所示电路.闭合开关S,L的实际功率为1.8W.则电源电压是 ____ V,此时通过R的电流是 ____ A.
读图—某地区等高线地形图,完成下列问题。