Complete the sentence: We will start the meeting __ all the members are here.

• A. As
• B. When
• C. Once
• D. Until

Answer: (B)

Choosing a time conjunction to link a future action to a condition is what this item tests. The sentence means the meeting will begin at the moment everyone is present, so the word that cleanly marks that specific time is when. It signals a clear point in time after which the action happens, which fits the intended meaning perfectly.

The other options don’t fit as neatly. As can imply simultaneity or reason rather than a precise starting moment. Once is close in meaning, but the standard, neutral choice here is when, which clearly introduces the exact time the meeting will start. Until would describe a period leading up to a point, which would reverse the intended sense.