Rule: Gerund after 'be used to'. The phrase 'be used to' means 'be accustomed to'. When it is followed by a verb, that verb must be in the gerund form (-ing). Therefore, 'to living' is the correct structure. The 'to' in this case is a preposition, not part of an infinitive. Option (a) 'to live' is the infinitive form and is incorrect. Option (c) 'to have lived' is a perfect infinitive. Option (d) 'live' is the bare infinitive. Both are grammatically wrong in this context.

Rule: Vocabulary - Antonyms and Confused Pairs. The sentence describes someone who 'believes everything'. This person is gullible or too ready to believe things. The word for this is 'credulous'. Option (a) 'cynical' and (b) 'skeptical' mean the opposite: being distrustful or doubtful. Option (d) 'incredulous' is often confused with 'credulous', but it means 'unwilling or unable to believe something'. The person described is the opposite of incredulous.

Rule: Phrasal Verbs and Diction. The sentence structure requires a verb that means 'to regard something as being caused by'. The correct phrasal verb is 'attribute to'. It properly links the effect (success) to the cause (marketing strategy). Option (b) 'contributed to' means 'to help to cause or bring about', which is close but 'attributed to' is more precise for explaining the reason for a result. Option (c) 'distributed' means to give out shares of something. Option (d) 'retributed' is not a common English verb in this form; the noun is 'retribution'.

Rule: Vocabulary and Context. The context is 'to combat terrorism', which is a serious issue requiring significant power. 'Sweeping' is an adjective that means 'wide in range or effect', often used to describe powers, changes, or reforms. It correctly implies the law gives extensive and far-reaching powers. Options (a) 'meager', (b) 'nominal', and (d) 'trivial' all mean small, insignificant, or existing in name only, which would be inadequate for combating terrorism.

Rule: Prepositions - Besides vs. Beside. The sentence adds another piece of information (he is a painter) to the first piece (he is a musician). 'Besides' is a preposition meaning 'in addition to' or 'as well as'. This correctly fits the additive nature of the sentence. 'Beside' (without the 's') is a preposition meaning 'next to' or 'at the side of', which is about location and makes no sense here. 'Except' means 'not including' and would create a contradiction. 'Apart' is used in the phrase 'apart from', which can mean 'besides' but is not a single-word option here.

Rule: Collocations and Precise Meaning. The sentence discusses telling two very similar things apart. The correct phrasal verb is 'distinguish...from', which means to recognize or treat (someone or something) as different. Option (b) 'separate' is usually followed by 'from' but implies physically moving them apart, not just telling the difference. Option (c) 'divide' is incorrect and not followed by 'from' in this context. Option (d) 'isolate' means to cause someone or something to be alone, which doesn't fit.

Rule: Vocabulary and Cause and Effect. The effect described is 'preventing her from winning the competition'. This is a negative outcome caused by 'a series of minor errors'. The verb must reflect this negative impact. 'Marred' means to impair the appearance of; to disfigure or spoil. It correctly describes how errors damaged her performance. Option (a) 'enhanced' means to improve. Option (b) 'embellished' means to make more attractive. Option (d) 'lauded' means to praise. All three are positive verbs and contradict the context.

Rule: Subjunctive Mood with 'It's high time'. The phrase 'It is time' or 'It is high time' is used to indicate that something should be done now or should have been done already. It is followed by a subject and a verb in the simple past tense to express this sense of urgency or slight impatience. Therefore, 'started' is the correct verb form. Option (a) 'start' is the base form, (c) 'should start' includes a modal, and (d) 'will start' is the future tense; all are grammatically incorrect in this specific structure.

Rule: Vocabulary and Purpose. The purpose of a 'treaty' between 'warring nations' is typically to create peace. The verb chosen must reflect this positive intention. 'Foster' means to encourage or promote the development of something, which is a suitable word for promoting peaceful relations. Options (a) 'disrupt', (c) 'sever', and (d) 'jeopardize' all have negative meanings that are contrary to the purpose of a peace treaty.

Rule: Collocations and Prepositions. The verb must fit with the preposition 'from'. The phrasal verb 'refrain from' means to stop oneself from doing something. This fits the context of being advised not to make statements. Option (b) 'indulge' is followed by 'in'. Option (c) 'proceed' is followed by 'with' or 'to'. Option (d) 'partake' is followed by 'in' or 'of'. None of the other options collocate correctly with 'from' in this context.