Quiz on "The Past Perfect Continuous Tense"

Welcome to your Quiz on "The Past Perfect Continuous Tense"

Fill in the blanks with the past perfect continuous tense of the verb in the brackets:

She _______________ (visit) her grandmother for 2 years before her grandmother passed away.
The doctor ____________ (practice) surgery for 20 years before he retired.
The pied piper ______________ (attract) the mice with the music of his flute for many days before he guided them to the river to be drowned.
The scientists _____________ (recover) data for their experiments much before the professor asked them to do so.
The child ______________ (play) for an hour before his teacher arrived.
The teacher was very angry as he ____________ (wait) for a long time before we arrived.
When the teacher entered the classroom on Monday, her eyes were red. I think she __________ (cry).
When we saw the boy on the pavement, he seemed very frail and tired. I think he ____________ (not/eat) for many days.
When he woke up, he realized that he _____________ (sleep) for 15 hours!