银汞合金调制中受潮可导致（）
A.强度下降
B.蠕变值下降
C.体积收缩
D.产生延缓膨胀
E.都不正确
参考答案：D
为了减少门锁滚轮噪音，常在门锁滚轮外缘包一层薄薄的橡胶外套.（）
Many of the electric and electronic products we purchase and consume today are what some industrial experts call " homogeneous toys".
A．identical
B．homosexual
C．unrelated
D．distinguishable
