用所给短语的适当形式填空。 | |
2. He's _______ smoking, for it's not good for health. 3. David _______ till 12:00 p.m. last night, because he had too much homework to do. 4. My father used to collect coins, but now he _______ collecting stamps. 5. Mary often _______ her friends on the phone for a long time. |