单项选择题
Environmental loading consists of the forces caused by wind，waves，and（）.
A.drilling B.soil reactions C.temperature D.current
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（）.
单项选择题 Daymarks marking the starboard side of the channel when going towards the sea are（）.
