English

The idiom "Hitting the Nail on the Head" means doing something exactly right or performing a task with precision. Option A correctly captures this meaning, while the other options do not reflect the idiomatic usage.

The correct article usage is 'The earth moves around the sun.' 'Earth' and 'sun' are unique celestial bodies, so the definite article 'the' is used before both.

The analogy compares 'Forecast' to 'Future' as a prediction relates to what is yet to come. Similarly, 'Regret' relates to 'Atone' because regret is feeling sorry for past actions, and to atone is to make amends for them. 'Past' and 'Sins' are related to regret but do not complete the analogy as well as 'Atone'.

"Anna Karenina" is a famous novel written by Leo Tolstoy, a renowned Russian author. The other options are poets and playwrights unrelated to this novel.

The original direct speech is in present tense: "What a teacher you are!" When converting to indirect speech, the tense shifts back to past tense, so "you are" becomes "he was." Therefore, option B correctly reflects this change.

The word 'chary' means cautious or wary. Its antonym is 'bold,' which means showing courage or willingness to take risks, the opposite of cautious. 'Careless' is related but implies negligence rather than the opposite of cautiousness.

The idiom "above-board" means honest and open, without any attempt to deceive. Therefore, option C, "Honest," is the correct meaning of the idiom.

The correct preposition to use with 'covered' in this context is 'with'. We say 'covered with snow' to indicate that snow is spread over the mountain.

The correct preposition to use with 'called' in this context is 'on', which means to visit someone. The sentence should read: 'I called on him but he was very busy in his work.' The other options do not fit grammatically or idiomatically.

A 'connoisseur' is someone who has expert knowledge and appreciation, especially in the arts or fine things. Therefore, 'Lover of art' best matches the meaning among the options provided.