差压式流量表是根据节流造成压差的原理制成的。

阅读理解

     Life is like the four seasons. Now I am very old, but when I was young. it was the spring of my life. I was born,

I played a lot, and then I started school.  I learned many new things. Like a flower, I grew bigger every day. There

were happy days and sorrowful days: some days the sun shone, and some days it didn't.

     In my twenties, I had a good job. I was strong and happy. Then I married and had a child. In those days, I didn't

have much time to think. Every day I was busy and worked very hard. And so, I started to get some white hairs.

The summer of my life passed quickly.

     Then the days got shorter. Leaves fell from the trees. My child was a university student, and then an engineer.

My home was much quieter. I started walking more slowly.

     One day I stopped working. I had more time. I understood this was my autumn, a beautiful time when the trees

change colour and give us delicious fruits.

     But the days kept getting shorter and colder.

     Winter has come. I am older and weaker. I know I do not have many days left, but I will enjoy them to the end.

1. The writer was very busy in the _____ of his life.

A. spring

B. summer

C. autumn

D. winter

2. According to the passage, which of the following ages is during the autumn of his life?

A. 15.

B. 33.

C. 62.

D. 87.

3. What does the underlined word "sorrowful" mean in this passage?

A. Sad.

B. Exciting.

C. Wonderful.

D. Pleasant.

4. Which of the followings is TRUE?

A. The writer was an engineer.

B. The writer had a garden with flowers.

C. The writer was always happy as a child.

D. The writer now is old and weak, but still he enjoys his life.

5.  The best title of the passage can be _____.

A. Four Seasons

B. My Life

C. Four Seasons in a Year

D. Four Seasons in My Life

对任意实数x，点P（x，-2x+3）一定不在（　　）

A．第一象限

B．第二象限

C．第三象限

D．第四象限

简述教学中的感知规律。

手动葫芦可分手拉葫芦和（）两种。

在正常情况下，导游人员为旅游者提供的导游讲解服务比旅游生活服务更为重要，而且前者正是导游人员的本职工作。