Hello fellow italki users, I am preparing to take an English proficiency test and in writing section we are required to show our skills by using various grammatical structures. The more divers grammar we use the better our scores get. So could you please recommend structures to improve my writing stylistically and grammatically? <o:p></o:p>

Structures like: 1- expensive yet effective 2- If not the most important... one of the most important …<o:p></o:p>

3- Had he studied he would not have failed his tests.<o:p></o:p>