Unit 3 What were you doing when the UFO arrived?教案
3. he shouldn’t go to bed so late.
4. you should take a photo.
5. he should put some pictures on the walls.
三.
1. while i was walking to school i saw a cat in a tree.
2. while i was walking past the car it exploded.
3. he said he was living in london.
4. i saw you while you were speaking to the teacher.
5. i was watching tv at 8pm yesterday.
四. 1. b 2. c 3. d 4. b 5. c