单项选择题
Ships at sea are in urgent need of MSI because they are（）various kinds of danger.
A.subject for B.liable to C.easy to meet D.always encounter
单项选择题 In the GMDSS, MSI broadcasts will be made on two dedicated systems:（）and（）.
单项选择题 International SafetyNet and Navtex Services promulgate MSI by means of（）.
单项选择题 With the help of modern technology, ships are able to receive automated broadcast of safety messages（）.
