Select the most appropriate option that can substitute the underlined segment in the given sentence. My cousin works day and night to achieve success in life.

Correct — A. The underlined phrase is day and night, and it is an adverbial hanging off the verb works: it says how long he works, not what he works at.

So the replacement must be able to sit in that same adverbial slot and carry the same sense of unbroken effort.

Around the clock means all through the twenty-four hours, without stopping. He works around the clock is both idiomatic and identical in meaning → option (a).

Why the others are wrong

• (b)
  great dealing — There is no English phrase great dealing. The real idiom is a great deal, meaning a lot, and even that measures quantity rather than duration, so it cannot stand in for day and night.
• (c)
  vale of tears — Vale of tears is a noun phrase for the world seen as a place of sorrow and suffering. It names a thing, so it cannot follow works as an adverbial of time.
• (d)
  a handful — A handful is a noun phrase meaning a small quantity, or a person who is hard to manage. He works a handful is not English and says nothing about how long he works.

An idiom-substitution item asks for two matches at once, and candidates usually check only the first.

The meaning must match: day and night means continuously. The grammatical class must match too: day and night is an adverbial, so only an adverbial phrase can replace it.

Of the four options, three are noun phrases or non-phrases and fail the second test before meaning is even considered. Around the clock passes both.

Key facts

• Around the clock means continuously, all day and all night, and works as an adverbial, as in the helpline runs around the clock.
• The idiom meaning a lot is a great deal, as in she travels a great deal.
• Vale of tears is a noun phrase for the world regarded as a place of sorrow.
• A handful means a small number of something, and of a person, someone difficult to control.

Common traps

• Choosing an option because it sounds like an idiom, without testing whether it can follow works.
• Reading a handful as hard work, when it means a small quantity or a difficult person.
• Treating great dealing as a form of a great deal, which is not how that idiom is built.

No directly related past PYQ was found.