“One or two free admission days at slow times.”“Slow times”here means _____.

If several fixed navigational lights are visible at the same time，each one may be positively identified by checking all of the following EXCEPT what against the Light List?（）

（）is an area within the radiotelephone coverage of at least one VHF coast station in which continuous Digital Selective Calling is available.

O'Neal works hard. He is often seen _______ heavily before his teammates have even arrived at practice.( )

为什么VHF通信属于近距离通信？

船用VHF通信设备属于（）距离的通信设备。

Before he arrived at the farmer's house, the writer expected to see Milly lying_______?

When Jack arrived, he learned Mary （） for almost an hour.

Jitter is an unwanted variation of one or more characteristics of a periodic signal in electronics and telecommunications and（）refers to call issues that cause variations in timing or time of arrival.

How many minutes before midnight is it if one hour ago it was five times as many minutes past 9 pm？

Sometimes lights are（）by fog，haze，dust，smoke，or precipitation which may be present at the light，or between the light and the observer，and which is possibly unknown by the observer.

This is to advise you that MV Water Way arrived at Sheerness at 1000 hours on May 14th and the formalities for entering the port were passed at 1040 hours on the same day.Now she is in all respects ready and fit to discharge her cargo of grain in bulk. Theses sentences are likely to appear in（）.