A.5s B.30s C.45s D.1min
A.遇險(xiǎn)報(bào)警 B.現(xiàn)場(chǎng)示位 C.常規(guī)通信 D.船位查詢
A.發(fā)出緩慢的“滴滴”聲 B.發(fā)出急促的“滴滴”聲 C.發(fā)出連續(xù)的聲響 D.不發(fā)聲