Spotting Errors

The given sentence is perfectly correct.

Error of modal usage. As per rules, double usage of modal is incorrect. 'Must' and 'have to' both show type of obligation, and are not used simultaneously. Use either of the two, and not both of them.

Case of pronoun usage. For persons, we use pronoun 'who', and 'which' is used for places and things.

The subject 'basic' is singular, but the verb 'are' is plural. The phrase should be 'The basic... is' or better yet, 'The basics... are'. Using 'basic' as a singular noun is awkward, but if we accept it as the subject, it requires a singular verb.

The word 'interested' is incorrect here. Paintings cannot be 'interested' (curious). The correct word should be 'interesting' (causing interest) or perhaps 'intriguing' to describe appealing artworks. 'Interested' shows curiosity, which objects cannot have.

The phrase 'only handful' is missing the article 'a'. The correct expression is 'only a handful' when referring to a small number of people or things. 'Handful' is a countable noun requiring an article.

The preposition 'on' is incorrect in the phrase 'she was on'. When describing situations or circumstances, we use 'in' - 'the situation she was in' not 'on'. 'On' typically means physically on top of something.

The word 'intrigued' is a past participle/adjective describing how someone feels, but here we need an adjective to describe the trip. The correct word is 'intriguing' (present participle) to maintain parallel structure with 'adventurous'. 'Adventurous and intrigued' doesn't match grammatically.

The subject 'a piano' is singular, so the verb must also be singular. 'There were' is plural - it should be 'there was a piano'. Subject-verb agreement requires matching singular subjects with singular verbs.

The causative construction 'is having' requires either a past participle 'replaced' ('is having replaced') or the present participle 'being replaced' ('is having... being replaced'). 'Replace on' is incorrect because -ing forms cannot directly follow causative 'have' in this context.

Relative clauses referring to things (steps) should use 'that' or 'which', not 'what'. 'What' functions as a fused relative pronoun meaning 'the thing that' and creates incorrect structure here. The correct phrases are 'steps that require' or 'steps which require'.

The sentence describes a past event (resigned), so the condition must also use past tense. 'Becomes' is present tense - it should be 'became' to maintain consistent past tense narration. The sequence of tenses requires matching past contexts.

The correct term is 'aquatic sports' (without 's' on aquatic). 'Aquatic' is already an adjective describing water-related activities. Adding an 's' creates an incorrect form. The standard usage is 'aquatic sports' as a compound term.

The passive voice construction requires the past participle 'handled', not the present participle 'handling'. The action is being done TO the tasks BY the operators, so it must be 'is handled' (passive), not 'is handling' (active). Present continuous passive uses 'is being handled'.

Conditional sentences about past hypothetical situations use 'would have' + past participle. 'Would lost' is incorrect - it must be 'would have lost'. Also, for a past unreal condition, 'didn't take' should ideally be 'hadn't taken' for full parallel structure, though the main error is in the first clause.