19. The dashed line arrow printed on the separate traffic lane means _____ direction of traffic flow. (A). common (B). established (C). recommended (D). optional

20. 當兩動力船舶於”CROSSING”情況而有碰撞危機時，下列何者屬於讓路船舶？ (A). The vessel that has more risk, such as tanker, chemical ship. (B). The vessel that has more manoeuver ability, such as high speed, double propeller ship. (C). The vessel which has the other on her own port side. (D). The vessel which has the other on her own starboard side.