Milk quickly goes bad in summer it is in a fridge (冰箱).
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.