15. __________ made his mother worried.
If _________ the same treatment again, he is sure to get well.
—Was his father very strict with him when he was at school?—Yes. He had never praised him _________ he became one of the top students in his grade.
—I wonder if I could possibly use your car tonight. —_________. I'm not using it anyhow.
He _________ the boy's ignorance and sold him a worthless learning machine.
Tony can't have received the invitation. _________,he would have attended your birthday party yesterday.