计价员计价时可使用的笔为
A．黑色钢笔
B．蓝色钢笔
C．红色钢笔
D．黑色铅笔
E．蓝色圆珠笔
参考答案：A,B,E
—"I stayed at a hotel while in New York."
—"Oh, did you? You _____ with Barbara."
A．could have stayed
B．could stay
C．would stay
D．must have stayed
某量程为0～10MPa的计量仪表，其允许最大误差为0.05MPa，则其精度等级是（）。
A、0.5
B、0.05
C、0.005
D、0.0005
