单项选择题
On a ship crane，the load chart relates the allowable load to the combination of boom length and（）.
A.boom angle B.boom strength C.load radius D.cable strength
单项选择题 Oil product samples should be taken from the（）.
单项选择题 For any given pedestal crane，when the boom is lengthened，the lifting capacity is（）.
单项选择题 For a given weight of cargo，the stress on the heel block of a cargo boom（）.
