用适当的介词填空。

1. There are two windows ________ the wall.

2. The broom is ________ the door. I can’t see it.

3. There is a dog ______ the tree. It can’t get down.

4. Where is the photo ________ your family?

5. There are some big apples _______ the tree.

吸烟可致肺癌但不是每个吸烟者都会得肺癌，即吸烟者肺癌发生率＜100%；另外不是每个肺癌病人以前都吸烟，即肺癌病人以前的吸烟率＜100%，此实例的病因组合符合

A．充分而且必要病因
B．充分但不必要病因
C．不充分且不必要病因
D．必要但不充分病因
E．以上都不是