Error Spotting – Choose the part (A–D) that contains the grammatical error, or choose No error if the sentence is fully correct. Sentence (parts correspond to options below): A) In order to save petrol, B) motorists must have to C) be very cautious D) while driving along the highways.
Correct Answer: motorists must have to
Introduction / Context:This tests modality and the redundancy of stacking must with have to. In standard usage, must and have to both express obligation; combining them is ungrammatical or at least nonstandard in formal writing.
Given Data / Assumptions:
- Purpose clause: In order to save petrol
- Modal sequence: must have to
- Intended meaning: obligation/recommendation for motorists
Concept / Approach:Use one marker of obligation: either must or have to. Choose must for strong speaker-imposed necessity or have to for external necessity. Do not stack them together.
Step-by-Step Solution:
Step 1: Identify duplicated modality: must + have to.Step 2: Decide on tone: advice with strong necessity fits must.Step 3: Correct to motorists must be very cautious or motorists have to be very cautious.Verification / Alternative check:Substitute: They must be cautious vs They have to be cautious. Both are grammatical; the stacked form is not.
Why Other Options Are Wrong:
- A) Purpose phrase is fine.
- C) Complement be very cautious is grammatical.
- D) while + -ing clause correctly marks time/circumstance.
Common Pitfalls:Learners often overemphasize necessity by doubling modals. Use one clear marker.
Final Answer:Option B contains the error. Use must be or have to be, not must have to be.