取样时应对样坯、试料和试样做出标记，以保证始终能识别取样的位置及方向。
参考答案：对
计算：-24的结果为（ ）
A．-8
B．8
C．-16
D．16
I _____ Wang Tao in the street yesterday. We _____ each other since he went to Beijing.
A．met, didn’t seen
B．have met, hadn’t seen
C．met, haven’t seen
D．met, hadn’t seen
