[单选] If the capacity of a centrifugal pump decreases gradually over a long period of time, you should replace the （）.

以下哪个命令用于修改文件的读、写、执行权限（）。 cp。 chmod。 chown。 chgr。 The deviation ordered by the Admiralty for strategic reasons in wartime（）to a general average act，because the masters obeying the order had no opportunity of exercising their own judgment or discretion. not amounting。 not to amount。 does not amount。 has not amount。 《八十天环游地球》中印度的地形是顶朝北、底朝南的正放大三角形。 《八十天环游地球》中一个星期后，福克先生坐着商船蒙古号开到了埃及苏伊士。 简述PPPoE的发现阶段包括的五种报文，并分别说明它们对应的代码域填充值。 If the capacity of a centrifugal pump decreases gradually over a long period of time, you should replace the （）.