In keeping with the apparent concern to keep material well within the grasp of the students for which it is designed, the writers seem particularly careful about making questions simple and focusing on material and points that are readily grasped and appreciated. While this will very likely satisfy some basic needs, and while there are many places where even in their simplicity questions are probing and may lead to useful discoveries, there are times when one feels that some increase in "difficulty" and depth (particularly in the strictly "comprehension" sections) is called for — especially as one progresses towards the end of the course. Sections of Unit 16 (multiple choice questions) could do with revision in this light.