用所给词的正确形式填空。 ( talk, help, read, cost, keep, change, do, visit, go, sit) 1. ________ it ________ much to live here? 2. The teacher looked at the clean classroom and said we ________ a good job. 3. The Smiths ________ greatly in the last two years. 4. He heard her singing aloud in the next room, so he _____ in a louder voice. 5. It was said that some foreigners ________ our class the next week. 6. They have done what they can ________ us stop the sandstorm. 7. Why are there so many people over there? Let's go and see what ________ on. 8. My family ________ at table when the door bell rang. 9. It's very cold in the room. Let's make a fire ________ us warm. 10. What do you think ________ about at the meeting tomorrow?