单项选择题
A.Oil vapour in air piping are dangerous
B.Explosion will cause oil vapouring in air lines
C.Oil vapour in air piping should be drained
D.Oil in air piping should not be drained
单项选择题 In usual marine applications, bellows joints are designed and fitted to accommodate straight line axial movement only and the associated piping requires adequate anchors and guides to prevent misalignmentAccording to the above sentence, which of the following statements is true?（）
单项选择题 Maximum and minimum working temperatures must be considered when choosing the joint, which must be so installed that it is neither over-compressed nor over-extendedThe bold and italic word "which "probably means （）.
单项选择题 Stainless steel is material commonly used for temperatures up to 50℃; beyond that and for severe corrosive conditions other materials are requiredThe bold and italic word “that” probably means （）.