"Brilliant" means exceptionally clever, intelligent, or shining with light. Its antonym is "Dull," which means slow-witted, lacking intelligence, or lacking brightness. Shining and Bright are synonyms of brilliant. Tough means strong or resilient and is not an antonym of brilliant.

"Ability" means the capacity or power to do something. Its antonym is "Incapability," meaning the lack of ability or capacity to do something. Skill and Power are synonyms of ability. Coarse means rough or rude in texture/manner and is completely unrelated to ability.

"Advocate" means to publicly support or recommend a particular cause or policy. Its antonym is "Oppose," meaning to actively resist or argue against something. Advocate and Oppose are direct opposites — one supports, the other resists. Discern, Remove, and Inspect are unrelated.

"Remember" means to recall or bring something back to mind from memory. This is the correct word when you cannot recall someone's name from your own memory. "Remind" means to cause someone else to remember something — it requires an object person (remind someone of something), not used for self-recall.

"Have been" (present perfect) is correct because the friendship started in the past (since we were children) and continues to the present. "Since" signals the use of present perfect tense. "Had been" (past perfect) would imply the friendship ended. "Are" misses the continuity from past to present.

"Insist on" is the correct verb + preposition collocation. The structure is "insist on + gerund (having)." "On having my fee paid" correctly follows the verb "insisted." "Insist to" and "insist in" are not standard English collocations — only "insist on" is grammatically correct.

The passage states: "Everyone knows that summer will not last. The power of all the wisest men and women in the world cannot keep it for us." The word "it" refers to summer. No human wisdom or power can prevent summer from ending — summer is what cannot be kept.

The passage ends with: "the corn becomes ripe, the ground and the world changes its green dress for a dress of autumn colors." The season described at the end is clearly autumn, when crops ripen and leaves change from green to autumn colors.

The passage opens with "Change does come after a prolonged cold weather" and describes the cycle from winter through spring, summer, and autumn. The central theme throughout is change — the inevitable, continuous change of seasons that no human power can stop.

The passage states: "Soon enough the days get longer and buds come out in the trees, birds sing, and the world puts on a green dress. Spring passes into summer." The world puts on its green dress during spring — the season when plants bloom and nature turns green after winter.

Per the answer key, "go into" replaces "go without saying" in this sentence. "Go into" means to investigate, examine, or proceed with plans in detail. The sentence means they advised the speaker to go into (examine or proceed with) their plans carefully.

Per the answer key, "bear with" replaces "bear upon." "Bear with" means to tolerate or be patient, which fits "in time of difficulty." "Bear up" means to remain strong under pressure and would also work idiomatically, but the answer key designates C (bear with) as the intended answer.

Per the answer key, D is selected. However, "blind to" is the standard English idiom meaning unable to notice or acknowledge something. "Blind to the shortcomings of his son" is the grammatically and idiomatically correct form in standard English usage.

Per the answer key, "in case of" best replaces "now or never" in this context. This replaces the idiomatic expression with a conditional phrase that fits the sentence structure — he comes to see me "in case of" need or occasion.

Per the answer key, "by luck of" replaces "by stroke of" in this context. "By a stroke of luck" is a common idiom meaning through a fortunate chance. The phrase "by stroke of" in the original is being corrected to its proper idiomatic form relating to fortune or luck.

"Incongruous" means not in harmony with the surroundings, out of place, or inappropriate. "Absurd" is its closest synonym, meaning wildly unreasonable or out of place. Both words describe something that does not fit its context. Mellow, intoxicate, and inadvisable carry very different meanings.

"Sequel" means something that follows as a continuation or result of something earlier. "Result" is its closest synonym in the sense of something that follows from a previous event or action. In literary terms, a sequel follows a previous story — the key meaning is "that which follows."

"Endeavour" means a serious attempt or effort to do something, especially something new or difficult. "Effort" is its closest synonym, both conveying the idea of applying energy and determination toward a goal. Short-lived, arrogance, and wrong notion are unrelated meanings.

"Retrograde" means moving backward, returning to a worse condition, or declining from a better to a worse state. "Regressive" is its closest synonym, meaning tending to return to a former or less developed state. Both words describe backward movement or decline.

"Embark" means to begin a journey or start a new project or activity. "Commence" is its closest synonym, meaning to begin or start. Cargo and weight relate to ships (a common association with embark), but they are not synonyms. Siderate is an unrelated term.

"Because of its" is the correct prepositional phrase. "Because of" is used before nouns and noun phrases to express reason. "Its motion and mass" are the reasons for kinetic energy. "Because" alone (options A and C) requires a full clause with subject and verb, not just a noun phrase.

"All of whom" is the correct relative pronoun phrase. "Whom" is used as the object form of "who" in relative clauses referring to people. The phrase "all of whom" correctly introduces a non-restrictive relative clause that provides additional information about the five sons.

"A few" is the correct phrase meaning a small number of. "A few feathered creatures" means some, but not many, creatures inhabit the arctic. "Fewer" is used in comparisons (fewer than). "As few as" requires a specific number to follow. "A few" works independently as a determiner before a plural noun.

"Than those" correctly uses the plural pronoun "those" to refer back to the plural noun "bones." In comparisons, the pronoun must agree in number with the noun it replaces. "Bones of the elderly" compared to "those (bones) of young people." "That" would be used for a singular noun.

"A part to the whole" is the correct phrasing. The sentence compares a part to the whole — this requires both the indefinite article "a" before "part" and the definite article "the" before "whole." Option C: "a part to the" correctly uses both articles in the right positions.