单项选择题
There are salvage operations（）position 120.0N 12.5E.
A.on B.at C.in D.above
单项选择题 When it is accepted to remain on the frequency indicated，you should say（）.
单项选择题 When the changing of a VHF channel / frequency is accepted，say（）.
单项选择题 Our company is a professional one，and you may rely（）it.
