People thought _____ hard to live without the medicine.
Great changes _________ in Nanjing since the1990s.
My mother _________ a history teacher.
–Have you finished your homework? – _________ . Just half of it. How about you?
– _________ you ________ your lost football? _Yes, I have. I _________ it an hour ago.
Though he __________ the book three times, he hopes to read it again.