问题 单项选择题

关于汽轮机设备的组成和作用叙述不正确的为( )。

A.汽轮机的排汽仍具有一定的压力和温度,因此仍具有一定的热力势能,这部分没有转换成机械能的能量称为冷源损失
B.由于汽轮机排气口处的压力高于进汽压力,在这个压力差的作用下蒸汽向排汽口流动,其压力和温度逐渐降低
C.具有较高压力和温度的蒸汽经主汽门,调节阀进入汽轮机
D.汽轮机是将蒸汽的热力.势能转换成机械能,借以拖动其他机械旋转的原动机

答案

参考答案:B

阅读理解

阅读理解

     Hundreds of years ago, a Roman army came north from England to make war on Scotland. The Scots, a brave people,

loved their country very much. They fought hard to drive the enemy out of Scotland, but there were too many of the

Romans .It looked as if the Romans would win.

     One night, the leader of Scots marched his soldiers to the top of a hill. "We will rest here tonight, my men," he said,

"Tomorrow we will fight one more battle. We must win or we will die."

     They were all very tired, so they ate their supper quickly and fell asleep. There were four guards on duty, but they

too, were very tired, and one by one, also fell asleep.

     The Romans were not asleep. Quickly they gathered at the foot of the hill. Slowly they climbed up the hillside, taking

care not to make a sound. Closer and closer they came to the sleeping Scots. They were almost at the top. A few minutes

more, the war would be over. Suddenly, one of them put his foot on a thistle (蓟). He cried out and his sudden cry woke

the Scots. In a moment, they were on their feet and ready for battle. The fighting was hard but it did not last long. The

Scots wiped out the Romans and saved their country.

     The thistle is not a beautiful plant. It has sharp needles all over it. Few people like it. But the people of Scotland liked

it so much that they made it their national flower.

1. Hundreds of years ago there was a war between _____.

A.Roman army and North England

B.Roman army and the Scots

C.England and Scots

D.A brave people and the Scots

2. At first it looked as if the Romans would win because _____.

A.the Scots were not brave

B.the Roman army was so strong

C.the Romans had the support from the Scottish

3. "We must win or we will die. "What the leader of the Scots said means _____.

A.they were sure to win

B.they couldn't escape from death

C.they would win and then they would die

D.they must try hard to win ,otherwise they woule be killed .

4. The Romans climbed up the hill quietly because _____.

A.they didn't want to wake the Scots

B.they wanted to reach the top

C.they wanted to catch the four guards first

D.they were afraid of the sharp needles of the thistle

5. The people of Scotland made thistle their national flower because _____.

A.it is a beautiful plant

B.it is fresh and lovely

C.it had so many sharp needles all over it

D.it was the thistle that helped the Scots to win the battle

单项选择题