认证后产品的监督管理包括：在证书有效期内认证机构对获证产品的监督和认证产品的市场监督管理。
参考答案：对
He spoke English so well that I took _______ for granted that he was an American.
A．that
B．this
C．which
D．it
改按天气恶劣难以辨认信号的办法行车遇地面信号与机车信号显示不一致时，如何办理？
