English

The correct option is 'if he had seen' because in reported speech, the past perfect tense is used to refer to a past event. The sentence is indirect speech reporting a question about the keys, so 'if he had seen' is grammatically correct.

The word 'witnesses' correctly fits the sentence as it refers to people who have seen an event, especially a crime, making it the appropriate choice. The other options do not fit grammatically or contextually.

The phrase 'too good to be true' is a common English expression meaning something is so good that it is hard to believe. Therefore, 'too' is the correct word to fill in the blank.

The word 'puerile' means childish or immature, so the synonym that best matches is 'Immature'. The other options do not convey the same meaning.

The term 'Cellophobia' is not recognized as the fear of beauty. The specific phobia related to fear of beautiful people, especially beautiful women, is called 'Venustraphobia.' None of the options given (Claustrophobia, Cynophobia, Cellophobia, Chronophobia) correctly define fear of beauty. Claustrophobia is fear of confined spaces, Cynophobia is fear of dogs, Chronophobia is fear of time. Since none of the options correctly define fear of beauty, the question is factually incorrect as posed. However, among the options, 'Chronophobia' is a recognized phobia (fear of time), while 'Cellophobia' is not a standard term. Therefore, the question should be corrected or clarified. Alternatively, if the question is about fear of time, then Chronophobia (D) is correct. Given the options, the best approach is to note that none of the options mean fear of beauty, and the correct term is 'Venustraphobia' which is not listed. Hence, the question is invalid as is.

The sentence requires the present simple tense for habitual actions or general truths. 'Don’t believe' is the correct negative form in present simple. 'Not believe' is ungrammatical, 'am not believing' is incorrect because 'believe' is a stative verb not usually used in continuous form, and 'will not believe' indicates future tense, which does not fit the context.

The word 'disdain' means to regard with scorn or contempt, so its synonym is 'scorn'. The other options do not share this meaning.

The word 'advice' is an uncountable noun, so it cannot be preceded by the article 'an' or the quantifier 'one'. The correct choice is 'some' to indicate an unspecified amount of advice.

The word 'motive' best fits the blank as it specifically refers to the reason or cause behind an action, especially in contexts involving crimes or attacks like bombings. While 'aim', 'objective', and 'purpose' are similar, 'motive' is the most appropriate choice here.

The correct collocation is 'take no notice of' something, meaning to ignore it. The other options are not standard English collocations in this context.