Complete the sentence: It was an American, in 1919. At _________ time, the bags were mainly used by tea companies to allow customers to try the tea before buying it.

Complete the sentence: It was an American, in 1919. At _________ time, the bags were mainly used by tea companies to allow customers to try the tea before buying it.

• A. This
• B. Which
• C. That
• D. When

Answer: (C)

The key idea is using a word that points to a specific moment in the past. When we refer to a particular time previously mentioned, we say “at that time.” Here the event happened in 1919, so “at that time” fits perfectly, marking a definite past moment and flowing naturally with the verb to describe what happened. That time is a fixed noun phrase after the preposition at, which is why the other options don’t work well. “This time” would refer to the present or a moment very close to the present, which isn’t appropriate for describing 1919. “Which time” isn’t a correct construction after at in this context, and “when” would require a different sentence structure rather than a simple noun phrase. So the best choice is that, giving: At that time, the bags were mainly used...

The key idea is using a word that points to a specific moment in the past. When we refer to a particular time previously mentioned, we say “at that time.” Here the event happened in 1919, so “at that time” fits perfectly, marking a definite past moment and flowing naturally with the verb to describe what happened.

That time is a fixed noun phrase after the preposition at, which is why the other options don’t work well. “This time” would refer to the present or a moment very close to the present, which isn’t appropriate for describing 1919. “Which time” isn’t a correct construction after at in this context, and “when” would require a different sentence structure rather than a simple noun phrase. So the best choice is that, giving: At that time, the bags were mainly used...