在正交设计中，因子都是二水平，可以选择的正交表______。A．L4(23) B．L

When David Williams left the college, he went to Australia. When he returned to England for a visit twenty years later, he decided to go back to his old college.

David was very glad when he found out that his old college teacher was still teaching there. He went to visit the old man, and after they had an interesting talk, the teacher went out to get something. While he was away, David saw an exam paper on the desk. He looked at the date on it and saw that it was given to the students a week ago. David picked the paper up and read it. When  the teacher came back, David said to him, ”Mr. Smith, I’m sure that these are right the same questions that you asked us in our exams twenty years ago! How is that possible?”

“Yes, that’s right,” agreed the teacher. “The questions are the same, but the answers have changed.”

45. David went to______  after he left the college.

A. England       B. Australia      C. another college       D. his teacher’s office

46. David felt ______ when he found out that his college teacher was still teaching there.

A. worried      B. sorry      C. surprised       D. happy

47. The students took the same exam_____.

A. twenty years ago         B. while David’s teacher was away

C. a week ago              D. while David read the paper

48 Can you guess why the teacher still used the same exam paper twenty years later? Because______.

A.times have changed, answers have changed, too  B  different students have the same answers  

C. the students like to take the same exam       D. the teacher loved his students very much

气缸总容积与燃烧室容积比值称为：（）

A、冲程

B、行程

C、压缩比

《端午的鸭蛋》课文结尾，作者写到了东晋的车胤“囊萤”夜读的故事。这段文字在文中有什么效果？

___________________________________________________________

苍耳子经炒黄后可

A．改变药性

B．降低毒性

C．缓和药性

D．降低刺激性

E．增强疗效

1847年，赛义德·阿里自称为先知马赫迪，写了巴布教的经典（）。

A.《古兰经》

B.《圣经》

C.《佛经》

D.《默示录》