A.(A20)
B.A20
C.$A$20
D.A$20
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你可能感興趣的試題
A.在MS-DOS方式下用MD命令
B.在“資源管理器”的“文件”菜單中選擇“新建”命令
C.用“我的電腦”確定磁盤或上級文件夾,然后選擇“文件”菜單中的“新建”命令
D.在“開始”菜單中,選擇“運行”命令,再執(zhí)行MD命令
A.會話層
B.數(shù)據(jù)鏈路層
C.用戶層
D.應(yīng)用層
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最新試題
翻譯:The total quantity of petroleum now thought to exist on Earth is about 14 trillion gallons. In weight that is only one-ninth as much as the total existing quantity of coal and ,at the present moment, petroleum is being used up much more quickly. At the present rate of used, the worlds supply of petroleum may last for only thirty years or so.
翻譯:After the casing string is run, the next task is cementing the casing in place. An oil well cementing service company is usually called in for this job although, as when casing is run,the rig crew is available to lend assistance.
翻譯:The HF-HCI mixture (usually 3-percent HF and 12-percent HCI) then is injected. The HF reacts with calys, sand, drilling mud, or cement filtrate to improve permeability near the well-bore.The HCI will not react and is present to keep the PH low, preventing precipitation of HF reaction products. Sent to keep the PH low, preventing precipitation of HF reaction products.
翻譯:In these early days, as lamp oil, was the important product and the main objects of refining was to extract as much of it as possible from the crude. Lubricants and some fuel oil were also sold, but gasoline was burnt off as unwanted and bitumen was also largely useless.
翻譯:A porous medium has a permeability of one darcy when a single phase fluid of one centipoise viscosity that completely fills the voids of the medium, will flow through it under conditions of viscous flow at a rate of one cubic centimeter per second per square centimeter cross sectional area under a pressure or equivalent hydraulic gradient of one atmosphere per centimeter.