Improve the bracketed part of the sentence by choosing the most appropriate alternative: "When I last saw Ravi, he (had been running) to catch his bus."

Introduction / Context:
This question tests your understanding of English verb tenses, especially how to narrate past events and ongoing actions. The sentence describes what Ravi was doing at the specific moment when the speaker last saw him. Choosing the correct tense makes the time relationship between the two actions clear and natural in English.

Given Data / Assumptions:

• Main sentence: "When I last saw Ravi, he (had been running) to catch his bus."
• We must decide if "had been running" is correct or if another form expresses the meaning better.
• Options: ran, was running, had run, no improvement.
• The time reference "when I last saw Ravi" points to a definite point in the past.

Concept / Approach:
English often uses the past continuous tense to describe an action that was in progress at a specific time in the past. The structure is "was/were + -ing form". The past perfect continuous "had been running" is used when we emphasise how long an action was happening before another past event. Here, the natural idea is simply that Ravi was in the middle of running at the moment the speaker saw him. Therefore, past continuous "was running" fits best. The approach is to compare the time relationship and choose the tense that most clearly shows an ongoing action at a point in the past.

Step-by-Step Solution:
Step 1: Identify the two actions: (a) I last saw Ravi (b) he was trying to catch his bus. Step 2: Notice that the seeing happened at one particular moment in the past, and the running was an action in progress at that moment. Step 3: For an action in progress at a specific past time, English uses the past continuous: "he was running". Step 4: Test option "was running": "When I last saw Ravi, he was running to catch his bus." This sounds natural and correct. Step 5: Test option "ran": "he ran to catch his bus" suggests a simple completed action after the seeing, which does not highlight that he was already in motion when seen. Step 6: Test option "had run": implies that his running was completed before the last time the speaker saw him, which conflicts with the intended meaning. Step 7: Evaluate "had been running": this tense emphasises duration before another event, but here the exam style and natural usage favour the simpler past continuous. Step 8: Conclude that "was running" is the best improvement.

Verification / Alternative check:
Grammar references often use examples like "When I saw him, he was running down the street" to illustrate the past continuous. They reserve the past perfect continuous for contexts such as "He was tired because he had been running for an hour." The exam sentence does not focus on the duration of Ravi's running, only on what he was doing at that moment. This confirms that "was running" is the most appropriate choice.

Why Other Options Are Wrong:

• ran: Simple past suggests a finished action and does not emphasise that the action was in progress when he was seen.
• had run: Past perfect indicates a completed action before another past event, which changes the intended sequence of actions.
• no improvement: "had been running" is grammatically possible but stylistically less natural and not the best choice for the usual exam expectation in such sentences.

Common Pitfalls:
Learners sometimes overuse complex tenses like past perfect continuous because they appear advanced, even when simpler forms are more natural. Another common error is not noticing the time marker "when I last saw", which signals that we are fixing a particular moment in the past. Always decide which action is ongoing and which is the reference point, then choose past continuous for the ongoing action at that time.

Final Answer:
The correct improvement is "was running", so the sentence becomes: "When I last saw Ravi, he was running to catch his bus."