In the following question, a sentence is given with a part in brackets that may be grammatically incorrect. Choose the alternative that improves the bracketed part. If no improvement is needed, select the option "No improvement". A small makeshift stage (was construct) with a red curtain for a backdrop.

Introduction / Context:
This sentence improvement question checks understanding of verb forms and passive voice in English grammar. The sentence describes the creation of a small makeshift stage with a red curtain. The bracketed phrase “was construct” sounds incorrect and must be examined. The learner must identify the correct tense and form of the verb “construct” to maintain grammatical accuracy.

Given Data / Assumptions:
- Original sentence: “A small makeshift stage (was construct) with a red curtain for a backdrop.”- Option A: “are constructed”- Option B: “was constructed”- Option C: “were constructed”- Option D: “No improvement”- We assume that the action took place in the past and that the subject “A small makeshift stage” is singular.

Concept / Approach:
The phrase clearly aims to express a passive action in the past: a stage was built by someone, though the doer is not mentioned. In passive voice, the structure is “was” or “were” plus past participle. The base form “construct” is wrong here; it should be “constructed.” We must also choose the correct auxiliary verb form, singular “was” or plural “were,” to agree with the subject “stage.” Therefore, the correct answer must be “was constructed.”

Step-by-Step Solution:
Identify the subject. The subject is “A small makeshift stage,” which is clearly singular.Identify the intended tense. The context suggests a completed past event, so the past tense is appropriate.Recognise that the sentence is in passive voice because the stage receives the action of building. For such passive constructions in past simple tense, the form is “was” plus past participle for singular subjects.Check Option B: “was constructed.” This fits the structure perfectly: singular auxiliary “was” plus past participle “constructed.”Option A, “are constructed,” is a present tense passive form and does not match the narrative past context.Option C, “were constructed,” uses plural “were” and cannot agree with the singular subject “stage.”Option D, “No improvement,” is wrong because “was construct” is grammatically incorrect.

Verification / Alternative check:
Replace the bracketed portion with the selected answer and read the full sentence: “A small makeshift stage was constructed with a red curtain for a backdrop.” This sentence is smooth and grammatically correct. It clearly conveys that someone built a temporary stage and that it had a red curtain behind it. Testing the other alternatives in full sentences confirms their unsuitability, especially due to tense mismatch and lack of subject verb agreement.

Why Other Options Are Wrong:
“Are constructed” uses present tense and would be suitable in general statements like “Small stages are constructed for school events.” It does not fit a specific past event.“Were constructed” is plural and would fit a sentence like “Small makeshift stages were constructed,” but the subject here is singular.“No improvement” is incorrect because “was construct” violates the rule for passive voice, which requires the past participle “constructed.”

Common Pitfalls:
Students sometimes overlook the difference between base verbs, past forms, and past participles, especially in passive structures. Remember that in the passive voice you always need “be” plus a past participle, not the bare verb. Another common mistake is ignoring subject number when choosing between “was” and “were.” Carefully matching singular or plural subjects to verbs prevents such errors.

Final Answer:
The correct improved form of the bracketed part is was constructed, so the sentence should read: “A small makeshift stage was constructed with a red curtain for a backdrop.”