单项选择题
Cast iron and gunmetal fittings are used freely in small sizes at moderate pressure; large fittings, those for high pressure and temperature are cast or mild steelIn the above sentence, the word “those” means （）.
A.east iron firings
B.mild steel fittings
C.small fittings
D.large fittings
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相关考题
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单项选择题
Wrought iron has an inherent resistance to corrosion but is not to be had freely , its place has been taken by the cuprous alloysAccording to the above sentence , which of the following statements is true?（）
A.Wrought iron can resist liquids flow
B.It is difficult to attain the wrought iron
C.Wrought iron should be combined with cuprous alloys
D.The cuprous alloys have mere disadvantages than wrought iron -
单项选择题
Seamless mild steel is used for steam (also copper for moderate pressure and temperature), h-pair, feed discharge and all oil fuel pressure pipingsAccording to the above sentence, which of the following statements is not true?（）
A.Both seamless mild steel and copper may be used for middle pressure steam
B."hpair" means high pressure air
C.The feed piping of the boilers can be made of seamless mild steel
D.All oil pipings are made of mild steel -
单项选择题
Cast irons weakness in tension and under shock loading limits its use to low pressure steam, air, oil and low speed water fittingsThe above sentence, most probably means （）.
A.cast iron has weakness
B.cast iron can stand up shock loading
C.cast iron fittings are only suitable in low pressure situation
D.east iron fittings are not suitable in low pressure situation
