Structured programming practices (1) rise to Pascal, in which constructs were introduced to make programs more readable and better (2) . (3) provided a combination of assembly language and high-level structure to create a general-purpose language that could be used from system to application programming. Next came object orientation, which is (4) of a methodology and design philosophy than a language issue. This is (5) by the addition of so-called OO extensions to current languages, such as application.

（2）（）

A.structure

B.structured

C.constructs

D.structures

使用空气一乙炔焰的火焰原子吸收分光光度计，在下列情况下应采取什么措施
(1)分析灵敏度低，怀疑被测元素在火焰中形成了氧化物。
(2)怀疑存在化学干扰，例如磷酸盐对钙的干扰。
(3)发射线强度很高，测量噪声小，但吸收值很低，很难读数。