Though most sentences in English will adhere to certain basic rules when it comes to structure, there are a few structures that are irregular, meaning they do not necessarily follow the traditional rules. The passive , the causative, the subjunctive, and inversions are all structures with specific functions that you need to familiarize yourself with.
Ex: The new project will be supervised by the IT department. (passive)
The VP of Operations had his assistant make copies of the minutes for his clients. (causative)
It is crucial that all documents be submitted in triplicate. (subjunctive)
Had I known you were coming to dinner, I’d have baked a pie. (inversion)
These structures are important to master as they provide the writer access to different approaches toward the sentence. This in turn helps establish sentence variety and style, which makes the written work more interesting and creates a better flow for the reader to follow.