Grammar exercise helps individuals to learn the correct form of English. The given sentence can be written as "Leila has been a nurse since 1999" and in second sentence "we haven't met since our last year at high school".
<h3>What is the meaning of since?</h3>
The word since is generally used with point of time in the past.
The given sentence is showing a point in the life of the given persons.
Thus, the sentence can be written by using since as "Leila has been a nurse since 1999" and in second sentence "we haven't met since our last year at high school".
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