Which of the following is true about the politician

A．He had proposed the same policy 2 years before the speech.

B．He did mention his old advocacy in his speech.

C．There was no time for the politician to talk about his advocacy.

D．His speech was just the opposite of what he had advocated 2 years before.

屏蔽线用螺装或铆装方式适用于频率（）场合。

A、低于500KHZ

B、高于100KHz

C、低于100KHz

D、高于500KHz