单项选择题
I am ready（）tow line.
A.cast B.to cast of C.cast off D.to cast off
单项选择题 How should the letter O be pronounced when spoken on the radiotelephone?（）
单项选择题 How（）the cargo at loading port?
单项选择题 Channel 13 (156.65 MHz)，the designated bridge-to-bridge channel，may NOT be used to（）.
