In this English grammar question on error spotting, read the complete sentence "I was taken by surprise when I came face to face with my school friend" and identify the part that contains an error, or mark that there is no error.

Introduction / Context:
Error spotting questions test your ability to recognise standard, natural English usage. The sentence given here describes a common situation in everyday life using an idiomatic expression. Your task is to see whether there is any grammatical or usage error in any of the three marked parts, or whether the entire sentence is correct and therefore "No error" should be selected.

Given Data / Assumptions:
• The sentence is: "I was taken by surprise when I came face to face with my school friend." • Part A: "I was taken by surprise". • Part B: "when I came". • Part C: "face to face with my school friend." • Option D states that there is "No error".

Concept / Approach:
The phrase "taken by surprise" is a correct and common idiom that means someone was unexpectedly surprised. The expression "came face to face with" is also a fixed idiom meaning that you suddenly meet someone in person, often unexpectedly. The verb tenses and prepositions must be checked, as well as agreement and word order. If all parts are grammatically correct and idiomatic, the correct answer will be "No error".

Step-by-Step Solution:
Step 1: Examine Part A, "I was taken by surprise". The passive construction with "was taken" is correctly used here to show that an event affected the speaker, and the phrase "by surprise" is standard. Step 2: Check Part B, "when I came". The conjunction "when" correctly introduces a time clause describing the occasion on which the surprise occurred. Step 3: Examine Part C, "face to face with my school friend." The phrase "face to face with" is a well accepted idiom, and the object "my school friend" is correctly placed. Step 4: Confirm that the tenses match. The event clearly happened in the past, and the past simple "came" and passive "was taken" are appropriate. Step 5: Since no grammatical or idiomatic error is found in any part, the sentence is correct as it stands.

Verification / Alternative check:
To double check, try rephrasing the sentence in another correct way, such as "I was very surprised when I suddenly met my school friend." This rephrasing keeps the meaning unchanged, showing that the original idiomatic expressions carry the intended sense correctly. If you compare with authentic English usage in books and articles, you will find both "taken by surprise" and "came face to face with" used in exactly this way.

Why Other Options Are Wrong:
Selecting Part A as erroneous would mean claiming the idiom "taken by surprise" is wrong, which is not true. It is fully correct. Choosing Part B would suggest there is a tense or structural error in "when I came", which is also not the case; the clause is fine. Choosing Part C would mean rejecting the idiom "face to face with", which is again a standard and correct expression.

Common Pitfalls:
In error spotting, some learners feel that every question must contain an error in one of the parts, so they hesitate to choose "No error". Examiners intentionally include fully correct sentences to test your confidence and to ensure that you are not changing correct English out of over correction. Another pitfall is to doubt correct idioms simply because they sound slightly formal or old fashioned, even though they are standard. Get used to seeing many examples of idioms in context so that you can recognise them quickly.

Final Answer:
There is No error in the sentence.