填空 1. G was once much used for lighting and is now used for cooking and heating. 2. Modern life depends on good t . 3. Eating too much c is bad for your teeth. 4. We should learn much more history k . 5. They are waiting for their friends on the p at the station. 6. He always has some d ideas in his mind. 7.I have collected a few a coins these years. 8. They'd like to d their. rooms with a Christmas tree and some fresh flowers.