当今世界，腐败现象遍及全球， * * 败已成为一个世界性的共同课题。这说明（ ） A

阅读理解。

     Look! This is a picture of my family. My mother is a doctor. My father is a teacher. This is my brother. His name is Harry. He's twelve. He's a student. That is my grandmother. Ah, this is me. My name is May. I'm ten. I'm a student. Harry and I are in the same school. 

根据短文内容，判断下列句子正（T）、误（F）。

( )1. This is a picture of my family.

( )2. My mother is a teacher.

( )3. Harry is my brother.

( )4. Harry is twenty.

( )5. Harry and I are in the same school.

仿照示例写句子。

　　在开满鲜花的小道上，一群群活蹦乱跳的少年追逐嬉戏是幸福的；在铺满黄叶的公园里，一对对银发夫妇相携漫步也是幸福的。

答：________________________。

如果一棵二叉树结点的前序序列是C、D、E，后序序列是E、D、C，则该二叉树结点的对称序序列________。

A．必为E、D、C

B．必为C、D、E

C．必为D、C、E

D．不能确定

下列管材中，适宜作为屋面雨水收集系统雨水管道的管材是( )。

A．不锈钢

B．钢管

C．承压塑料管

D．普通塑料管

生物酒精的优点主要有哪些？