Sentence examples similar to that I true from inspiring English sources

Suppose that (i) is true.

Case 1: Suppose that (i) holds true.

Is that true, I say?

"Is that true?" I asked the manager.

Is that true?" "I wouldn't hope," Hansen said.

Is that true?" I was genuinely confused.

"Is that true?" "That's not true," Mr. Ganim said.

Hence, we know that (i) holds true.

"Is that really true?" I ask cynically.

Is that really true?" I thought.

Is that true that everyone is undergoing?