In the following passage, some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives. Technical skill ____________ to the ability and knowledge to use the pedagogy, tools and techniques involved in the teaching and research of a specific subject. Ability in programming or software designing and operating a computer is, ___________ instance, a technical skill. There are two things a teacher should understand __________ transformational technical skills. In the first place, he must know __________ skill and what level of skill should be applied on a particular student. He should be ____________ enough with their potential to ask discerning questions. Secondly, a teacher must understand the role of each event organised and the transformational skill applied, and the inter relationships between the events and skills. a computer is, ___________ instance, a technical skill.

Introduction / Context:
This cloze question focuses on a common fixed expression in English used to introduce an example. The sentence describes ability in programming or software designing and operating a computer and explains that this ability is an example of a technical skill. Your task is to supply the correct preposition for that expression.

Given Data / Assumptions:
The relevant portion of the passage reads Ability in programming or software designing and operating a computer is, ___________ instance, a technical skill. We know that the writer wants to say that this ability is, for example, a technical skill. Therefore, the blank must be filled with a preposition that participates in a standard phrase meaning for example.

Concept / Approach:
In English, the idiomatic expression used to introduce an example is for instance. It has the same meaning as for example. The preposition for is fixed in this phrase and cannot be replaced by of, from, at, or by without sounding incorrect. Recognising such fixed combinations is essential for scoring well in cloze tests.

Step-by-Step Solution:
Step 1: Read the full clause Ability in programming or software designing and operating a computer is, blank instance, a technical skill.Step 2: Paraphrase it as Ability in programming is, for example, a technical skill.Step 3: Recall that the set phrase equivalent to for example is for instance.Step 4: Insert for into the blank to form the complete phrase for instance.Step 5: Check that the sentence now reads smoothly and correctly.

Verification / Alternative check:
Test each wrong option in the sentence. Of instance, from instance, at instance, and by instance are not used in standard English to mean for example. Only for instance is widely accepted in written and spoken English for this purpose. The rhythm and familiarity of the expression also make the correct answer easy to recognise once you know it.

Why Other Options Are Wrong:
of is used in phrases like in case of or of course, but not with instance in this pattern. from normally indicates origin or movement away and does not match the meaning needed here. at marks location or time, as in at home or at night, and is unsuitable. by can suggest agency or means, as in by car or by the teacher, but again does not produce a known idiom with instance. None of these alternatives convey the sense of providing an example.

Common Pitfalls:
One common error is to treat the blank as an isolated preposition choice and forget to recall fixed expressions that native speakers actually use. Another pitfall is confusing for instance with in this instance, which has a different structure. In cloze tests, always look for complete phrases that you have seen many times in authentic English, not just isolated grammar rules.

Final Answer:
The correct choice is for, giving the phrase for instance in the sentence Ability in programming or software designing and operating a computer is, for instance, a technical skill.