单词填空。根据句子内容和所给首字母填入适当的单词。

1. Mike usually goes to school by bus, but today he goes by b______.

2. The 2008 Olympic G______ will be held in Beijing.

3. Bill says he wants to j______the army when he grows up.

4. A stranger was knocking at the door, but she was afraid of  l______ him in.

5. Her mother became s______ ill and had to be sent to hospital at once.