单项选择题
A.opposite directions on the same line，tending to pull the material apart
B.opposite directions on the same line，tending to compress the object
C.opposite directions along parallel lines
D.the same direction along parallel lines
单项选择题 Sometimes it is desirable to connect a member both by riveting and welding. Which statement is TRUE concerning this procedure? （）
单项选择题 Should the vessel have no deratisation certificate at the time of her delivery，she（）be held to be unseaworthy.
单项选择题 Prior to burning or welding on a fuel tank on a ship，regulations require that an inspection be made. An entry in the unofficial logbook is required if this inspection is made by（）.