Engineering is ______ challenging course of study that requires ______ thoroughunderstanding of mathematics and science.

A．the; a

B．a; the

C．不填；不填

D．a; a

笔试测验的标准化一般包括对试题内容、施测方法、指导语、施测时限、评分标准、分数解释等主要环节的统一，标准化测试的最终分数解释必须以人为规定的标准为依据。