We promised to tell the truth . .?

Analyze the question: This is a question tag. The sentence is "We promised to tell the truth, ___?" We need the correct tag to complete it.

Concept: A question tag uses the same subject (as a pronoun) and the same auxiliary or tense as the main clause, but with the opposite polarity:

• Positive statement → negative tag
• Negative statement → positive tag

Step-by-step solution:

1. The main clause is "We promised..." The subject is we, so the tag must use we.
2. The verb promised is in the simple past tense with no auxiliary verb, so the tag uses did.
3. The statement is positive, so the tag is negative: didn't.
4. Tag: didn't we?

Checking the other options:

• A. isn't it uses "it" and the present tense, so it doesn't match "we promised."
• C. shouldn't we would need a main clause with "should," as in "We should tell the truth, shouldn't we?"
• D. wasn't it uses "it" and the verb "was," which doesn't match.

Answer: B. didn't we.

Tip: To form a tag, find the subject and the auxiliary verb. If there is no auxiliary, use do/does/did depending on the tense. Then flip the polarity. For example, "She sings well, doesn't she?" and "They left early, didn't they?"