你可能感興趣的試題

單項選擇題

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

單項選擇題

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