Auxiliaries, Modals, Adjectives and Adverbs

The phrase 'cent per cent' is redundant when used with 'merit list' or in general usage where '100 percent' is preferred. However, the error is in the tense usage: 'had topped' and 'had secured' are both past perfect, but the sequence of events is simultaneous or simple past. 'He topped the merit list and secured 100 percent marks' is more natural.

The past perfect tense 'had said' should be used instead of the simple past 'said' because the action of speaking occurred before the action of telling his boss. Therefore, the error lies in part D.

The word 'fast' is both an adjective and an adverb. 'Fastly' is not a standard English word. The correct adverbial form is 'fast'.

The relative pronoun 'which' is used for inanimate objects or animals. Since the subject includes a person (the farmer), the correct relative pronoun is 'who'.

In conditional sentences starting with 'if', the present tense is used in the 'if' clause to refer to the future. 'If I shall go' is incorrect; it should be 'If I go'.

When a specific past time (last week) is mentioned, the simple past tense must be used. 'Has come back' is present perfect and cannot be used with a definite past time marker.

The sentence describes a sequence of events in the past. 'The visitors left' should be 'the visitors had left' to indicate that their departure happened before he returned.

The sentence uses 'had known' (past perfect) in the first clause, implying a past context. The main clause should also be in the past tense, so 'he has gone' should be 'he went'.

The main verb 'was told' is in the past tense, so the subordinate clause must also be in the past tense. 'She has gone' should be 'she had gone'.

The first part of the sentence is in the past tense ('threw out'). Therefore, the purpose clause should also use a past tense form, changing 'has' to 'had'.

The idiom is 'a habit of doing something'. Therefore, 'to keep' is incorrect and should be replaced with 'of keeping'.

The word 'Hot' is an adjective and cannot function as the subject of the sentence. It should be the noun 'Heat'.

The sentence starts with a present tense verb ('are classified'). The subsequent verb 'suggested' should also be in the present tense ('suggests') to maintain consistency.

The phrase 'in what' is incorrect here. The correct relative pronoun to refer to the 'illusion' is 'in which'.

The word 'dimly' is an adverb, but it is modifying the noun 'light'. An adjective is required here, so it should be 'dim light'.

The word 'abundance' is a noun, but an adjective is needed to describe 'plant life'. It should be 'abundant'.

The word 'environment' is a noun, but an adjective is needed to modify 'stimuli'. It should be 'environmental'.

The structure 'very... that' is incorrect. The correct correlative conjunction is 'so... that'.

The parallel structure is broken. The list is 'observed, described, and... identified'. The addition of 'be' is redundant and grammatically incorrect.

The sentence contrasts the birth of man in Africa with the dispersal caused by the Ice Age. 'But' is the appropriate conjunction to show this contrast.

When referring to a unique historical event or specific item, the definite article 'the' is required, and the past tense 'was' is appropriate for a completed discovery.

The structure 'Not only... but also' requires inversion of the subject and verb in the first clause. 'Is seismology used' correctly follows this rule.

'Nil' is the appropriate term to describe a growth rate of zero in this context.

The sentence describes a general fact about the Giant Panda, which requires the simple present tense.

Sentences starting with 'Not until' require inversion in the main clause. 'Was there protection' is the correct inverted form.

The sentence expresses a future-oriented tendency or behavior for the embryo, making 'will try' the most appropriate choice.

The subject 'The belief' is singular, so the verb must be 'is known as' to complete the passive construction correctly.

The sentence requires a comparative structure to describe the knee's vulnerability. Option A correctly uses the phrase 'more likely to be damaged than' to establish the comparison between the knee and other joints.

The sentence contrasts nations with long coastlines against those that do not have them. 'None' acts as a pronoun referring back to 'coastlines', making it the grammatically correct choice.