单项选择题
Cracks may be prevented from developing at the corners of welded plating inserts by（）.
A.squaring the corners B.rounding the corners C.plug welding the corners D.slot welding the corners
单项选择题 Connecting elements of a mooring system should be fabricated from（）.
单项选择题 Chain slings are suitable for heavy slender articles，such as（）.
单项选择题 Chafing gear（）.
