
Answer:
Explanation:
Solution
Original: When Samuel finally gets here we will all go to the arena.
Correct: When Samuel finally gets here, we will all go to the arena.
When is a subordinate conjunction. It does not begin a main clause -- not in this sentence. It requires a comma.
Original: Once the office opens. I can issue you with a refund.
Correct: Once the office opens, I can issue you with a refund.
Same kind of answer as the one above. Once is acting a subordinate conjunction. It cannot form a main clause.
Original: Due to technical difficulties that were beyond our control the online interview will now be held at 9 am next Wednesday.
Correct: Due to technical difficulties that were beyond our control, the online interview will now be held at 9 am next Wednesday.
Due to is acting as a subordinate conjunction. It should have a comma when the conjunction ends.