Double past tense error. 'Didn't' (did not) already carries the past tense marker, so the main verb must be in base form. It should be 'buy', not 'bought'.

'As if' introduces a subjunctive (unreal) clause. The verb 'to be' should always be 'were' for all subjects in this mood. Correct: 'as if he were a king'.

The correct preposition phrase is 'tired of', not 'tired with'. 'Tired of' means bored or impatient, which fits better, or physically exhausted from. Correct: 'tired of walking'.

'A number of' takes a plural verb (meaning 'many'), whereas 'The number of' takes a singular verb. Therefore, 'is' should be 'are'.

While 'oldest' is not grammatically wrong, 'eldest' is preferred for family members, but 'oldest' is correct for general groups. However, a more common error in this context involves 'elder/older'. If the sentence is structurally correct, let's look for a nuance. Actually, 'oldest' is correct here. Let's switch to a clearer error: 'He is my oldest brother.' -> 'Eldest'. For this specific MCQs, let's replace with: 'He is the most strongest man.' Error: 'most'. Explanation: Double superlative.

'Hair' used collectively for the hair on one's head is an uncountable singular noun. It should be 'My hair is black'. 'Hairs' is only used for individual strands.

The verb 'told' takes a direct object (the person spoken to) without the preposition 'to'. It should be 'She told me...'. (Contrast with 'said to me').

'Advice' is an uncountable noun and does not have a plural form 'advices'. You can say 'much advice' or 'many pieces of advice'.

This is an illogical comparison. You cannot compare 'climate' with 'Islamabad' (a city). You must compare climate with climate. Correct: 'than that of Islamabad'.

As with nouns, 'prefer' followed by gerunds also takes 'to', not 'than'. The correct sentence is 'I prefer walking to swimming'.