In the following question, the sentence is given with a blank to be filled in. Choose the correct form of the verb to complete the sentence: She was uneasy because she __________ on a plane before.

Introduction / Context:
This question tests your understanding of tense usage in English, specifically the past perfect tense used to describe an earlier past event in relation to another past situation. The sentence describes a woman who feels uneasy in the past because, before that moment, she had no earlier experience of flying. Choosing the correct verb form shows whether you can correctly connect two past time points using appropriate grammar.

Given Data / Assumptions:
- Sentence: “She was uneasy because she __________ on a plane before.” - The main clause uses simple past: “She was uneasy”. - The blank describes an experience that happened (or did not happen) earlier than her uneasiness. - We must choose the correct verb form from the given options.

Concept / Approach:
In English, when we talk about a past state or event that is caused by an even earlier experience, we usually use the past perfect tense: “had” plus the past participle. Here, her uneasiness in the past is due to the fact that at that earlier time she had never flown before. So the correct structure is “had never been on a plane before.” This is a standard pattern when describing first-time experiences before another past reference point.

Step-by-Step Solution:
1. Identify the main tense: “was” indicates simple past. 2. Recognise that the clause after “because” refers to a state that existed before the time when she was uneasy. 3. Recall the structure of the past perfect: had + past participle (been). 4. Examine options: - “had never been” is correctly formed past perfect. - “never been” lacks an auxiliary verb and is incomplete. - “is never been” mixes present and passive elements and is ungrammatical. - “no improvement” would keep the incorrect bracketed form from the original prompt. 5. Therefore, “had never been” is the correct choice to indicate a lack of prior experience before that past moment.

Verification / Alternative check:
Compare similar sentences: “He was nervous because he had never driven a car before” or “They were excited because they had never visited the beach.” In both cases, the structure “had never + past participle” describes the earlier experience. Applying the same pattern to the given sentence confirms that “she had never been on a plane before” is the natural and grammatically correct form.

Why Other Options Are Wrong:
- “never been”: Missing the auxiliary “had”, so it cannot function as a complete verb phrase in this sentence. - “is never been”: Incorrect mixture of present tense “is” and past participle “been”, and does not match the past time reference. - “no improvement”: The original bracketed phrase is incorrect; therefore, no improvement is not acceptable.

Common Pitfalls:
Learners often forget to use the past perfect when talking about “first time” experiences before another past event. They may use only simple past or drop the auxiliary verb. Another common error is mixing tenses within the same sentence, which makes the timeline confusing. A good rule is: when one past situation explains the reason for another later past situation, especially involving prior experience, use “had + past participle”.

Final Answer:
The correct completion is had never been, so the sentence reads: “She was uneasy because she had never been on a plane before.”