In the following sentence, identify the part that contains an error in English grammar or usage. If the sentence is error-free, select 'No error': 'If it would / rain, they will / not come.'

Introduction / Context:
This question focuses on error spotting in conditional sentences, a frequent area of testing in competitive English examinations. The sentence given is divided into numbered parts, and the candidate must identify which part contains a grammatical error. The sentence is: If it would / rain, they will / not come. / No error. Understanding correct conditional structures, especially first conditionals, is essential to answering this type of question correctly.

Given Data / Assumptions:

• The full sentence reads: If it would rain, they will not come.
• The sentence is intended to talk about a possible future situation and its result.
• The parts are labelled as Part 1, Part 2, Part 3, and Part 4 (No error).
• We assume the meaning is: If it rains in the future, they will not come.

Concept / Approach:
English conditionals have fairly fixed patterns. The first conditional, which expresses a real and possible future situation, usually takes the form: If + present simple, will + base verb. For example, If it rains, they will not come or If you study, you will pass. We avoid using would in the if clause for real future conditions. Would is generally used in the main clause of second conditionals or in polite requests, not in the if part of a realistic future condition. Therefore, the correct pattern here should be If it rains, they will not come, not If it would rain, they will not come.

Step-by-Step Solution:
Step 1: Identify the type of conditional. The sentence refers to a possible future situation, so it is a first conditional.Step 2: Recall the standard form of the first conditional: If + present simple, will + base form.Step 3: Check Part 1: If it would. This uses would in the if clause, which is not correct for the first conditional.Step 4: Check Part 2: rain, they will. This part is acceptable as long as the if clause uses a present simple verb.Step 5: Check Part 3: not come. This completes the main clause as they will not come, which is correct for a result clause.Step 6: Part 4 is the No error option. Since we clearly see an error in Part 1, Part 4 cannot be correct.Step 7: Conclude that Part 1 contains the error and needs correction to If it rains.

Verification / Alternative check:
Rewriting the sentence in correct form gives If it rains, they will not come. This now fits the standard first conditional pattern perfectly. You can compare with other examples like If the shop opens, we will buy groceries or If she calls, I will answer. None of these use would in the if clause when the situation is considered realistic and possible. This comparison confirms that would in Part 1 is incorrect.

Why Other Options Are Wrong:

• Option B: Part 2, rain, they will forms a correct continuation once Part 1 is fixed to If it rains.
• Option C: Part 3, not come, correctly completes the future result clause will not come.
• Option D: Part 4, No error, is wrong because we have already identified a clear error in Part 1.

Common Pitfalls:
Learners sometimes think that adding would to the if clause makes the sentence sound more polite or formal, but in conditionals that describe real future possibilities, this is incorrect. Another pitfall is mixing up first and second conditionals. The second conditional uses If + past simple, would + base verb, as in If it rained, they would not come, which expresses an unreal or unlikely situation. Recognising whether the sentence talks about a real or unreal scenario helps in choosing the correct structure and avoiding such mistakes.

Final Answer:
The error is in Part 1: If it would, which should be corrected to If it rains.