It is very necessary for you to fully understand the task types before appearing the exam. There are sometimes YES/NO/NOT GIVEN questions and most of the time students are unable to identify NO and NOT GIVEN questions.
While reading the text you must look for the synonyms as well, to locate the right answer. If the information is there than you say YES. If the answer is WRONG than you write NO and if the information or answer is not mentioned than you write NOT GIVEN.
If you have any question feel free to ask me.