1) Make sure you extend your answers with, e.g. reasons, examples.
2) Remember you can respond to what your partner says in their answers.
3) Sometimes the examiner will ask you to discuss a question together and this may lead to a discussion between you. This may last more than one turn each, which is fine.
4) There is no right or wrong answer, students will not be judged on their opinions, only on the language they use to express themselves.
5) It's alright for students to admit they don't know much about a particular question. Rather than saying I don't know, use a more developed response e.g. I don't know much about that topic, so it's difficult for me to comment.