A.pressure changes in the air mass B.movement of the air mass C.the heterogeneous nature of the air mass D.upper level atmospheric changes
单项选择题Please wireless to let me know （） I am to anchor or to meet pilot．
A.which B.where C.what D.who
单项选择题Place names used should be those （）.
A.specified by international authorities B.specified by national authorities C.on standard map D.on the chart or Sailing Directions in use
单项选择题Pilot ladder is （） on port side．
A.equipped B.rigged C.put on D.put off
单项选择题Passage through the Suez Canal is operated on a （） system．
A.convey B.convoy C.escort D.conform
单项选择题On no account （）proceed without pilot in this water area．
A.the vessel B.shall not vessel C.the vessel should D.should vessel
