A lifeboat is weight tested by lowering to near the waterand loading to capacity with weight evenly distributed. Itis then lowered into the water and released. This test mustbe done at least once every（）.

A.3 knots in smooth water
B.6 knots in smooth water
C.3 knots in rough water
D.6 knots in rough water

A.be the first individual to board the craft
B.drain the hydraulic pressure before lowering the craft
C.have a list of the persons assigned to the lifeboat
D.All of the above

A.lift oars to vertical position，trim blades fore and aft with handles resting on the thwarts
B.complete the stroke，come to Oars，raise the oars smartly to the vertical，rest handles on footings and trim blades fore and aft
C.place oars in row locks directly from the boated position or from Stand by oars position
D.complete the stroke (when rowing in ahead motion)，raise the oars with crook of elbow to about 30 degrees，swing blades forward