Réponse:
1.) I lost it .
2.) I was very tired, so I lay down on the bed and went to sleep.
3.) Mary went to Australia for a while but she's back again now.
4.) He went out.
5.) I forgot most of it.
6.) I forgot.
7.) I had a headache earlier but I feel fine now.
8.) there was an accident.
9.) They haven't/not finished it.
10.) No, she just went out.