Improve the bracketed part of the sentence. The stranded pilgrims (had waited) in the bitter cold for more than two hours now.

Introduction / Context:
This sentence improvement question examines correct tense and aspect usage in a context that describes an action started in the past and continuing up to the present. The sentence talks about stranded pilgrims who have been in the bitter cold for more than two hours now. The phrase had waited must be checked against the time marker now and the duration phrase for more than two hours. The problem tests knowledge of present perfect continuous tense.

Given Data / Assumptions:

• The subject is the stranded pilgrims, which is plural.
• The action is waiting in the bitter cold.
• The duration is more than two hours.
• The adverb now indicates that the situation still continues up to the present.
• The original bracketed phrase is had waited, and the options include several present perfect and continuous forms.

Concept / Approach:
When an action began in the past and is still continuing at the present moment, English typically uses the present perfect continuous tense, formed with have been plus the ing form of the verb. The phrase for more than two hours now strongly suggests ongoing duration until now. Therefore, the correct form with a plural subject is the stranded pilgrims have been waiting. The original had waited is past perfect and does not match the now reference, and other options either mismatch subject or aspect.

Step-by-Step Solution:
Step 1: Identify the time relationship. The waiting began in the past and still continues up to now. Step 2: Recall that present perfect continuous is appropriate for such ongoing situations. Step 3: Build the structure: plural subject the stranded pilgrims requires have, followed by been and the ing form waiting. Step 4: Compare with the options. Has been waiting is singular, have been waiting is plural continuous, have waited is perfect but not continuous, and no improvement would keep the incorrect past perfect. Step 5: Choose have been waiting as the form that fits both subject number and desired aspect of ongoing duration.

Verification / Alternative check:
Consider a simpler example: They have been waiting for an hour now. This is clearly standard English. Changing it to They had waited for an hour now is incorrect because had waited usually refers to an action completed before another past action, not one continuing till now. In the exam sentence, the presence of now rules out past perfect. The same logic applies, confirming that have been waiting is the correct improvement.

Why Other Options Are Wrong:
has been waiting: This form is singular and would fit with a subject like he or she. It is incorrect with the plural subject the stranded pilgrims. have waited: This present perfect tense indicates a completed action with present relevance, but it does not emphasise continuous activity over a period, which the context demands. no improvement: Keeping had waited would describe a completed action before some other past event, which conflicts with the adverb now that refers to the present moment.

Common Pitfalls:
Students often confuse present perfect and past perfect forms and may think that had waited sounds more sophisticated. Another common error is to overlook subject number when choosing between has and have. To avoid such mistakes, always look for time markers like now, since, and for plus duration, which signal present perfect continuous. Matching tense to time expressions is crucial for scoring well in grammar based questions.

Final Answer:
The improved sentence is The stranded pilgrims have been waiting in the bitter cold for more than two hours now.