Choose the appropriate form of the tense for the given sentence.
When Jamil ______ at the university in 2010, Mr. kamil ______ there for 20 years.

- In the given sentence, the correct answer is 'enrolled & Had taught'
- In the first blank point of time has not been mentioned hence we can't use the perfect tense so conceptually we have to use the past indefinite tense and
- In the second blank the time reference is given i.e. 'for 20 years' hence with this point of time we have to use the past perfect tense.
Correct sentence: When Jamil enrolled at the university in 2010, Mr. Kamil had taught there for 20 years.