Answer:
The given sentence "Mr Bert had taught for five years" is already in the past perfect tense. However, if we want to change it to the past perfect continuous tense, we can do so by adding "been" and the present participle form of the verb "teach."
So, the sentence in the past perfect continuous tense would be:
"Mr Bert had been teaching for five years."
In this sentence, "had been teaching" is the past perfect continuous tense form of the verb "teach." It indicates that Mr Bert started teaching in the past and continued to do so for a period of five years before another past event occurred.
Here's an example to help illustrate the usage of the past perfect continuous tense:
"By the time he retired, Mr Bert had been teaching for five years. During that time, he had been dedicated to his students and had been making a positive impact on their lives."
Step-by-step explanation:
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