It was about 600 years ago _____ the first clock with a face and an hour hand was made .
Though I have often heard this song _______. I have never heard you _______ it.
Tony was very unhappy for _______ to the party.
Though ________ money, his parents managed to send him to university.
The research is so designed that once _______ nothing can be done to change it.
“What do you think made Mary so upset?” “_______ her new bike.”