It is quite ______for an SES operator to send a distress alert.
A. easy and expensive
B. simple and certain
C. dangerous and stable
D. simple and certainly
查看答案
It is possible for ships to receive safety message transmitted by Navtex station______
A. in any INMARSAT regions
B. n each NAVTEX area
C. at any distance
D. in Areas A3 and A4
微信支付 
支付宝支付