The clock struck（敲）eleven at night. The whole house was quiet. Everyone was in bed except me. Under the strong light, I looked sadly before me at a huge pile of that troublesome stuff they call “books”. I was going to have my examination the next day. “When can I go to bed?” I asked myself. I didn’t answer. In fact I dared not(不敢).
The clock struck twelve. “Oh, dear!” I cried. “Ten more books to read before I can go to bed!” We students are the most wretched creatures in the world. Dad does not agree with me on this. He did not have to work so hard when he was a boy.
The clock struck one. I was quite desperate now. I forgot all I had learned. I was too tired to go on. I did the only thing I could. I prayed, “Oh God, please help me pass the exam tomorrow. I do promise to work hard afterwards, Amen.” My eyes were so heavy that I could hardly open them. A few minutes later, with my head on the desk, I fell asleep.
小题1: The underlined word “wretched” in Paragraph 3 probably means ____________.
A．happy
B．disappointed
C．unhappy
D．hopeful小题2: Reviewing his lessons that night didn’t help him because ____________.
A．it was too late at night
B．he was very tired
C．his eyelids were so heavy that he couldn’t keep them open
D．he hadn’t studied hard before the examination小题3: What do you suppose probably happened to the author the next day?
A．He went to a church to pray again.
B．He passed the exam all by luck.
C．He failed in the exam.
D．He was punished by his teacher.小题4: The best title for the passage would be ____________.
A．The Night Before the Examination
B．Working Far into the Night
C．A Slow Student
D．Going Over My Lessons
的定义，可以看出以临界水深为界，当大于临界水深时，断面单位能量随水深增加而增加；在小于临界水深时，断面单位能量随水深增加而减小。 [解题关键] 首先要熟练掌握，断面单位能量的涵义，因为它是针对断面最低点的单位重力能量，与断面单位重力机械能不同，可以沿程减小、增加和不变。将
式两边对h求导，可以得到
。其随水深变化的规律就很容易判断。在大于临界水深时，Fr＜1，
，断面单位能量与水深变化同趋。