due to，look into，step up，make up，occur to，show up，take charge of，point out |
A fifteenyearold boy named Justin Foster in Dover，New Hampshire went missing two days ago. was not until the lunchtime the next day that he was found missing. His mother became(worry) and asked her husband to call the police. People offered various explanations for his (appear). Kelly，his sister said that Justin return home the night before and even heard him put on his favourite CD，just then she happened to see a large spaceship (fly) outside，so she thought Justin must (take) away by aliens. Some people also said that they themselves experienced this kind of thing. But Detective Sam Peterson，who took charge the case，said that there was really no hard (evident) that aliens took him and that they wouldn't give up until they found out had happened.
