The purpose of a narrative report is to describe something. Many students write narrative reports thinking that these are college essays or papers. While the information in these reports is basic to other forms of writing, narrative reports lack the "higher order thinking" that essays require. Thus narrative reports do not, as a rule, yield high grades for many college courses. A basic example of a narrative report is a "book report" that outlines a book; it includes the characters, their actions, possibly the plot, and, perhaps, some scenes. That is, it is a description of "what happens in the book." But this leaves out an awful lot.
It really depends on a number of factors, one of which is your understanding of the test and requirements of the band scores. If your English is suitable for the band score you are aiming for, you will only need to focus on exam skills to make sure you reach your potential. The skills will help you understand how to approach questions and what the examiner is looking for in your writing and speaking. Once you feel comfortable with all that, you will have a clear idea of how long you want to practice before your test. Whatever you decide, make sure you are frequently getting the band score you want in practice tests.
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