用气压焊焊接的钢轨焊缝缺陷主要是光斑、断面氧化和过烧。

阅读理解，判断正(√)误(×)。

      Ann had a dream last night. She was an astronaut. Ken was in her dream. He was an astronaut, too. They

were in the spaceship. Then they in space. There were many stars and planets. Mars was very cold. There

was no water. There was no air. There were no trees. but there were martians. They were afraid but the

martians were friendly. Soon they were friends. They had fun on mars. She had a good dream.

( ) 1. Ken had a dream last night.

( ) 2. Ann had a dream last night.

( ) 3. There were many stars and planets in the space.

( ) 4. Mars was very hot.

( ) 5. The martians were friendly.

( ) 6. Ann had a bad dream.

为了减少CO对大气的污染，某研究性学习小组拟研究CO和H₂O反应转化为绿色能源H₂。已知：

2CO(g)+O₂(g)＝2CO₂(g) ΔH =－566 kJ·moL^－1

2H₂(g)+O₂(g)＝2H₂O(g) ΔH =－483.6 kJ·moL^－1

H₂O(g)＝H₂O(l) ΔH =－44.0 kJ·moL^－1

（1）氢气的标准燃烧热△H  =          kJ·moL^－1。

（2）写出CO和H₂O(g)作用生成CO₂和H₂的热化学方程式：                                                 。

（3）H₂是一种理想的绿色能源，可作燃料电池；若该氢氧燃料电池以KOH为电解质溶液，其负极的电极反应式是                                                 。

血袋保存的时间是多少？

当鸡产蛋率达到（）时，停止限制饲养

A、5%

B、10%

C、20%

在施工过程中，以重要的技术工作，必须进行技术复核。砖石工程主要包括（），皮数杆上砖皮划分及其竖向标高，砂浆配合比。

A.墙身中心线位置

B.砂浆饱满度

C.砖石质量

D.垂直度