Step 1 — Analyze the sentence:
The sentence is: Study hard ___ you will not pass.
Here, the blank requires a word that shows a condition or consequence — if the condition is not met, failure will follow.
Step 2 — Suitable connector:
The word else fits perfectly. It is used after an imperative to mean “otherwise” or “if not.”
Step 3 — Apply the word:
The complete sentence becomes:
Study hard else you will not pass.
Step 4 — Conclude:
Thus, the correct word to fill the blank is else.
Answer: The correct answer is else.