某地区常遭水患，年平均受灾损失达240万元。为减少洪水灾害损失，该地区拟修建水坝，其

四根竹片长分别是1m，2m，3m和4m，用这四种竹片可以钉成的三角形有（      ）种。

阅读理解

      My name is Jim Green. I’m English. I’m fourteen. I’m in Class One. My friend, Tom, is in my class.

His sister’s name is Alice. She is twelve. They live in Beijing with their mother and father. Our Chinese

teacher is Mrs. Wang. She is very tall. She is very friendly (友好的), too. We all like her.

根据短文内容，判断下列句子正(T)、误(F)。

( )1. Jim and Tom are in Class One.

( )2. Alice is Tom’s sister.

( )3. Mrs. Wang is an English teacher.

( )4. They all live in China.

( )5. Mrs. Wang is a good teacher.

农村革命根据地经济建设的内容主要包括 

①打土豪、分田地 ②兴修水利 ③开展大生产运动 ④兴办工厂 [ ]

A．①②

B．①③

C．②④

D．③④

花生四烯酸在日光作用下可合成（）。

A.维生素C

B.维生素D

C.维生素B

D.维生素E

E.维生素B₁₂

下列不属于项目安全控制重点的是（）。

A．施工中人的不安全行为

B．施工中物的不安全状态

C．作业环境的不安全因素和管理缺陷

D．施工工期控制