When you open a file or run a program in a computer, a window appears on the desktop of your computer. The (67) of the window indicates which program you are currently working in arid its color will become blue if a window is active. When you click on The (68) , the window disappears and appears as a button on the taskbar. Clicking on a button in (69) will invoke a specific command.

A．menu bar

B．tool bar

C．scroll bar

D．status bar

水电站的三大设备是（）

A.水轮机、水轮发电机、调速器

B.水轮机、水轮发电机、电力变压器

C.水轮机、电力变压器、调速器

D.水轮机、调速器、电力变压器