单项选择题
The material used extensively as electrolytic protection around bronze propellers is（）.
A.brass B.copper C.lead D.zinc
单项选择题 The most important principle of the cargo stowage is（）.
单项选择题 The most important principle in the stowage is（）.
单项选择题 The most variable factor in the control of broken stowage is（）.
