If you have trouble deciding what each genre (essay, report, letter, proposal, review) is about, there are probably samples of those at the end of your book. As soon as possible you should also start your own collections of expressions useful for a particular genre.
> For details, examples and more, see page 29 onwards here:
> For examples of corrected writings, look here:
> Remember to check your collocations while writing, for example here: