Hii!
Frankly speaking, you are facing this problem completely because of your negligence. There are different set of rules for naming a compound as per the IUPAC nomenclature and the common name. If you pay attention to the rules, you get it.
Also, read the question carefully before answering. Read the question, repeat it in your mind, till you become clear of what is asked in the question, then only attempt it accordingly. Only focus and continuous practice can help you solve this problem.
Hope you understand.
Good luck!