The instructions are saying that you should attempt all the questions, regardless of whether they are multiple choice or fill-in-the-blank.
Here's a breakdown:
* Answer the multiple choice questions: This means you should choose the best answer from the options provided for each question.
* Fill in blanks if known: This means if you know the answer to a fill-in-the-blank question, you should write it in. If you don't know the answer, you can leave the blank empty.
It's important to note that the instructions don't necessarily mean you must know the answers to the fill-in-the-blank questions. You should still attempt them if you know the answer, but don't feel pressured to guess if you're unsure.