46. If an engineer applies aformula or a tabulation or a curve blindly, without knowing its history,its accuracy and the limits of its sapplicability,the results that he obtains will be neither intelligent nor practical.
如果一个工程师盲目地应用一个公式、一张图表或一条曲线,而对它的来历、精确度和应用范围却一无所知,那么他所得到的结果既不明智,也不实际。(without...applicability介词短语作谓语applies的条件状语。that引导定语从句,在句中作obtains的宾语。)
47.The neutron carries no electrical charge and in some respects acts as though it were composed of a proton and electron combined,with the positive charge of the proton neutralized by the negative charge of the electron.
中子不带电荷,并且有点像是由质子和电子结合而成的,质子的正电荷被电子的负电荷中和了。(in somerespects,“在某些方面”,“有点”。act as though,“表现得似乎”。as though引导方式方法状语从句,其谓语常用虚拟语气。句末with引出介词复合结构,对前句的谓语作补充说明。)
48.We know that the rate of cooling from above the critical range will greatly change the structure and therefore the properties of any steel.
我们知道,从临界温度以上冷却的速率会大大改变任何一种钢的结构,从而会改变其性能。(from above..,“从……以上",是双重介词。)