单项选择题
A bridge over a navigable waterway is being repaired. There is a traveller platform under the bridge’s deck that significantly reduces the vertical clearance. If required by the CG district commander，how will this be indicated at night?（）
A.Illumination by flood lights B.A quick flashing red light at each lower corner C.A strobe light visible both up and downstream D.Fixed amber lights under the extreme outer edges of the traveller
单项选择题 （）of the following items is not in the charge of Chief Officer in repairing operation.
单项选择题 （）about 20 sq.m to be sand-blasted.
单项选择题 Damaged bulkheads often take a permanent set which is independent of the panting or bulge caused by water pressure. To control this，you should（）.
