The Verbal Reasoning and Quantitative Reasoning sections are section-level adaptive. The first section of each measure (i.e., Verbal and Quantitative) is of average difficulty. The difficulty level of the second section of each of the measures depends on your overall performance on the first section.
For example, if you do very well on the first Quantitative Reasoning section, the second section of Quantitative Reasoning will be at a higher level of difficulty. The scoring for the Verbal Reasoning and Quantitative Reasoning measures takes into consideration the total number of questions answered correctly across the two sections, as well as the difficulty level of the sections.