Grammar structures are the framework for the way we use language and it is always good to have a clear understanding of how it works. You should not focus so much on learning fixed grammar structures, but learn through examples and maybe fixed phrases to enhance your vocabulary and make it easier to recall, for exercises like these see HERE
You need to remember that in the use of language, and especially for speaking and listening skills, many English speakers and natives in particular do not respect grammar structures. You should think of grammar as a guide, but not an exact science. To see more on how to understand native speakers, click HERE
Take a look at our FREE RESOURCES in PDF format and try some of our vocabulary exercises HERE.
For a full course to pass the B1 (PET), B2 (FIRST CERTIFICATE) or C1 (ADVANCED) see APPF.ES