西安地铁二号线车辆空压机的调压范围（）A、800-900KP B、700-900KPC

Is this your chair? [ ]

A. It's your desk.

B. It's my desk.

C. Yes, it is.

化简：2a-（2a-1）=______．

Keep your kids away from the _____ knives. They may cut themselves. [ ]

A. firm

B. pure  

C. sharp

D. good

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世界上第一台计算机的名称是

A．ENIAC

B．APPLE

C．UNIVAC-I

D．IBM-7000