单项选择题
The range of a SSB transmission is MOST affected by（）.
A.atmospheric noise and radiated power B.the frequency band selected and time of day or night C.interference and position of the moon D.radiated power and nearness to shore
单项选择题 The light rhythm of Morse (A) is shown on（）.
单项选择题 The following（）is a standard phrase.
