Question

If you want to learn to speak English fluently, you _________ work hard?

- might
-could
-should
-will​

Answer 1

will

Step-by-step explanation:

the answer is will

Answer 2

I believe your answer is the 4th choice: Will.

Since it's a question, "will" makes sense, but if it's a statement (ending with a period (.)) I'd go with "should."