下列数字中,有效数字位数为四位的是
A、【H+】=00050mol/LC
暂无解析
随着社会信息化的不断发展,隐私保护更有必要,下列属于侵犯隐私权的是()
close________(现在分词)
俗话说:“君子一言,驷马难追。”诚信的基本要求是()
JackisateacherofEnglish.Heisnotyoung,butheisnotold.Hehasaroundfaceandblackhair.Heistall.Therearefiftystudentsinhisclass.Theyalllikehim.Nowit'sintheafternoon.Look,somestudentsareworkingintheclassroom.Jackisthere,too.HeishelpingthemtostudyEnglish.Heisagoodteacher,andheisagoodfriendofthemall.
()1.WhatdoesJackdo?
A.Heisaworker.
B.Heisateacher.
C.Heisadoctor.
D.He'sanurse.
()2.Whatcolourishishair?
A.It'sblack.
B.Hisheiriswhite.
C.Itisbrown.
D.Hehasyellowhair.
()3.Howmanystudentsarethereinhisclass?
A.Therearefifteenstudentsinhisclass.
B.There'sfifty.
C.Hehasfifty.
D.There'refiftyinit.
()4.Jackisagoodteacher,isn'the?
A.Yes,heisn't.
B.No,heis.
C.Yes,he's.
D.Yes,heis.
()5.Whatarethestudentsdoingintheclassroom?
A.Theyarewalkingthere.
B.Theyaredoingtheirlessons.
C.Theyarehelpingtheirteacher.
某同学在做“测量小灯泡的电功率”实验时,选取两节干电池作为电源,使用的小灯泡额定电压为2.5V.
(1)请用笔画线代替导线,将图甲所示的电路连接完整;
(2)电路连接完成后,闭合开关,他发现灯泡不发光,电流表示数不为零,电压表示数为零,则该故障可能是由于灯泡_____(选填“断路”或“短路”)引起的;
(3)故障排除后重新闭合开关,移动滑动变阻器滑片P到某一位置时,电压表的示数如图乙所示,此时灯泡两端电压为_____V;若要使灯泡正常发光,他应将图甲中滑片P向_____(选填“A”或“B”)端移动;
(4)移动滑片,使电压表示数为2.5V,此时电流表的示数如图丙所示,则灯泡的额定功率是_____W.