单项选择题
If your vessel were proceeding down river (descending)，a green square marker with a green reflector border on the right bank would be a（）.
A.mile board B.dredging mark C.passing daymark D.crossing daymark
单项选择题 Environmental loading consists of the forces caused by wind，waves，and（）.
单项选择题 Entering from seaward，triangular-shaped daymarks are used to mark（）.
单项选择题 During the day，a vessel with a tow over 200 meters in length will show（）.
