The following sentence has been split into four segments. Identify the segment that contains a grammatical error. The company specialises at / designing, crafting and manufacturing / exquisite, high- quality furniture / of exceptional craftsmanship.

Correct — B. The verb specialise is fixed to the preposition in, never "at". A company specialises in designing, crafting and manufacturing furniture.

Nothing else in that segment is faulty: the subject "The company" is singular and "specialises" agrees with it. The single error is the preposition, which is why option (b) is the segment to mark.

Repair: "The company specialises in designing, crafting and manufacturing...".

Why the others are wrong

• (a)
  designing, crafting and manufacturing — The three gerunds are parallel and correctly follow the preposition that "specialises in" requires. A list of -ing forms after a preposition is standard, and nothing in it breaks.
• (c)
  of exceptional craftsmanship — Of is the right preposition for a phrase describing quality after a noun: furniture of exceptional craftsmanship. The phrase repeats the idea of high quality, but redundancy is a style fault, not a grammatical error.
• (d)
  exquisite, high-quality furniture — Two adjectives before a noun with a comma between them is correct, and high-quality is properly hyphenated as a compound modifier. The stem prints it as "high- quality" with a stray space, a typing slip rather than the fault being tested.

Error-spotting items usually turn on a fixed pairing rather than on a rule you can reason out. English attaches particular prepositions to particular verbs, and the pairing is learnt, not derived.

Specialise takes in. So do the related forms: a specialist in tax law, specialisation in robotics.

Once the preposition is settled, the rest of the sentence follows automatically — a preposition is followed by a gerund, so designing, crafting and manufacturing are the correct forms.

Key facts

• Specialise, or specialize, is followed by in, as in she specialises in tax law.
• A preposition is followed by a gerund, so it is specialises in designing, never specialises in to design.
• A compound modifier is hyphenated before a noun, as in high-quality furniture, but not after it, as in furniture of high quality.
• Repetition and wordiness are style faults, and this item asks for a grammatical error.

Common traps

• Marking the redundant phrase of exceptional craftsmanship because it reads badly
• Assuming the segment with a list of three verbs must be the faulty one
• Misreading specialises as a subject-verb agreement error

No directly related past PYQ was found.