He has lost his pen. He is _______ it everywhere.

The bus hit against a tree in the fog and __________to the deep valley, with ten passengers killed and twenty wounded.

There ______ a book, two pens and three pencils on the desk.

There are many volunteers ______ are helping the children in Sichuan.— And most of them are college students.

Tom, you didn’t come to my party last night?– I ________, but my mom hurt her back and I had to look after her.