Vocabulary is the key to doing well in IELTS Reading. Usually there are "keywords" in the questions that are similar to the words you need to find in the text. For example, if the text contains the word "global", the question might use the word "international".
The table below shows keywords for Test 4 in Cambridge IELTS book 4:
Try making your own keyword tables for other practice tests. It's a good way to improve your vocabulary, and it will help you to see how IELTS reading questions are made.