Spotting Errors

 'This kind of shoes' The subject is singular 'kind'.

 There is no error in this sentence.

Something which was 'hidden'.

When changing a question into indirect speech, the word order must change from interrogative to assertive. Therefore, would I should be replaced with whether I would or if I would. This maintains the correct structure for a subordinate clause.

The pronoun serves as the subject of the verb deserves in the relative clause, so the subjective form Whoever must be used. Whomever is the objective form and is incorrect in this position. The phrase we think is a parenthetical insertion that does not change the case of the subject.

The pronoun Everyone is singular and must be paired with a singular verb to maintain subject-verb agreement. Therefore, were should be changed to was. The prepositional phrase among the guests does not change the number of the subject.

In this context, improvement is an uncountable noun, which requires the singular verb has been. The plural verb have been is incorrect because the subject of the clause is singular. The rest of the sentence is grammatically sound.

The perfect participle construction having must be followed by the past participle form of the verb. Saw is the simple past tense, while seen is the past participle. Therefore, the correct phrase is having seen.

The sentence is grammatically correct as written. The phrase accustomed to is a fixed expression where to is a preposition, correctly followed by the gerund drinking. There are no errors in subject-verb agreement or word choice.

The sentence lacks a proper introductory structure for the first clause. It should begin with a present participle like Considering to function as an adverbial phrase. Alternatively, it could be split into two separate sentences.

The subject he is singular and requires the singular verb form gives to agree in number. While the reason is because is often considered redundant in formal writing, the subject-verb disagreement in part (d) is a more definitive error.

The word elixir begins with a vowel sound, so the indefinite article an must be used instead of a. This is a basic rule of English phonology and grammar. The rest of the sentence is correct.

 If it is an armless chair, sit on will be the correct usage. The correct usage in case of an armed chair will be 'sit in'. 

Certain adjectives derived from Latin, such as senior, junior, superior, and inferior, are followed by the preposition to instead of than. Therefore, senior than is incorrect and should be senior to.

The reciprocal pronoun each other is used when referring to two people, such as Romeo and Juliet. One another is generally reserved for groups of three or more. Thus, part (d) contains the error.