单项选择题
All the copper bars are（）different sizes.
A.at B.in C.by D.from
单项选择题 A vessel transferring provisions or cargo at sea shall display during the day（）.
单项选择题 A vessel engaged in replenishment or transferring persons，provisions or cargo while under way can be regarded as（）.
单项选择题 A hydraulic accumulator is designed to（）.
