Join the pair of sentences using the Past Perfect Tense. Make changes if necessary.
c. Dad finally answered the door. I was knocking on the door for at least five minutes.
d. We won a large cash prize in a lottery. We visited ten European countries.
c. Dad finally answered the door after I had knocked on the door for at least five minutes.
d. After we had won a large cash prize in a lottery, we visited ten European countries.
d. After we had won a large cash prize in a lottery, we visited ten European countries.