Bài Làm :
1. We switched off the lights before we went tobed.
-> Having switched off the lights we went to bed.
2. She had not slept for two days and therefore wasn't able toconcentrate.
-> Not having slept for two days, she wasn't able to concentrate.
3. Since I had not seen him for ages, I didn't recognizehim.
-> Having not seen him for ages, I didn’t recognize him.
4. I had not ridden a horse for a long time and found it very difficult to keep in the saddle.
-> Not having ridden a horse for a long time, I found it very difficult to keep in the saddle.
5. She had been to the disco the night before and overslept in themorning.
-> Having been to disco the night before, she overslept in the morning.