If better use is ________ your spare time，you’ll make good progress in doing your business.

A．spent

B．made of

C．used for

D．taken

带电更换绝缘子，在绝缘子串未脱离导线前，拆、装靠近横担的（）片绝缘子时，应采用专用短接线或穿（）方可直接进行操作。