The Critical Reading sections of the SAT (formerly called "verbal reasoning") consist of two basic types of questions: sentence completions and critical reading (short and long passages).
Two Critical Reading sections are 25 minutes long and one is 20 minutes long. Since one section of the test is experimental (although you won't know which one), you could have an additional Critical Reading section, as well.
The order of the sections and the number of questions may change, but at this time, the three sections total about 65 to 70 questions that count toward your score. These three sections generate a scaled critical reading score that ranges from 200 to 800. About 50% right should generate an average score.
The sentence completion questions are generally arranged in a slight graduation of difficulty from easier to more difficult. Basically, the first few questions are the easiest; the middle few are of average difficulty; and the last few are difficult. There is no such pattern for the critical reading passages or questions.