23．I’d love to join your visit to a local museum today, but I’m on a very ____ schedule —I’ve got a lot of work to do today.

A．ideal

B．entire

C．tight

D．Suitable

实施监视雷达进近时，航空器开始作最后进近前，进近雷达管制员应当通知航空器（）。

A.塔台频率

B.监视雷达进近服务在何点终止

C.机场能见度

D.RVR值