21. ‘Neither’ must be followed by singular verb and pronoun in formal written English. So ‘were’ should be ‘was’.
22. Most adverbs of manner are formed by adding –ly to adjectives. So ‘different’ should be ‘differently’ to modify the manner in which the chair is shaped.
23. ‘because’ is a prepositional phrase, so ‘as evening’ should be ‘like evening’. ‘As’ acts as a conjunction, while ‘like’ acts as a preposition.
24. Here ‘raised’ should be used instead of ‘risen’. To ‘raise’ means to move to a higher place, while to ‘rise’ means to go up.
25. Adverb is used to modify an adjective. So ‘profound’ should be changed to adverb ‘profoundly’ which modifies adjective ‘disappointing’.
26. ‘was’ should be ‘were’. In the unreal condition (contrary to fact or hypothetical), the past tense form of ‘be’ is always ‘were’.
27. The clause ‘many people believed’ establishes a point of view in the past. ‘is’ should be ‘was’ to maintain the point of view.
28. A ‘verb word’ must be used in a clause after an impersonal expression. ‘is’ should be changed to ‘ be’ after the impersonal expression ‘it is essential’.
29. ‘living’ should be ‘live’. (subject + used to + verb in simple form)
30. ‘because’ should be ‘because of’. (because of + noun)