Frankly, practise is the only solution. Practise practise practise. Once you complete a question, in the allocated time of course, check your answers.
This is beneficial as 1. You are in fact expanding your vocab and potentially you could utilise some of the nathanna cainte in your eachtra for instance.
2. Practising under exam conditions is paramount when studying.
It will become less difficult as you practise and broaden your vocab. For instance if you see a new word or nathanna write it down and learn if. Aim to learn 10 words/nathanna each night and you will be well on your way to procuring that A.