问题 选择题

下列是小东制作洋葱表皮细胞临时装片时所进行的几个相关步骤,请你将它进行正确的排序(  )

A.1→2→3→4→5

B.4→5→1→3→2

C.5→4→1→2→3

D.2→1→3→4→5

答案

制作洋葱表皮细胞临时装片的具体步骤是:用干净的纱布把载玻片和盖玻片擦拭干净,防止载玻片或盖玻片上有污点影响观察效果;把载玻片放在实验台上,用滴管在载玻片中央滴一滴清水,目的是为了维持细胞的正常形态;用镊子从鳞片叶的内表面撕取一块薄膜,可使光线通过,便于观察;把撕取的薄膜放在载玻片中央的水滴中,用解剖针轻轻地把水滴中的薄膜展开,目的是没有重叠,便于观察;用镊子夹起盖玻片,使它的一侧先接触载玻片上的液滴,然后缓缓放平,其目的是防止出现气泡;在载玻片的中央滴加碘液,另一侧用吸水纸吸引,重复2~3次,使染液浸润到标本的全部.为了对比明显,利于观察.所以正确的顺序是5→4→1→2→3.

故选:C.

完形填空
完形填空。
     Joe was driving home on a country road one winter evening. He spent several months looking for a new 
 1  since the factory he had worked in closed. It was a lonely road. Not many people had a reason to be on it 
 2  they were leaving.
     He almost didn't see a small car  3  at the side of the road. He thought the driver might need help, so he
pulled up in front of the car and got out. An old lady was in the car. At first she was worried. "He didn't look
  4 . He looked poor and hungry," she thought. He could see that she was  5 . He said, "I'm here to help you,
madam."
     All the lady had was a flat tire (瘪的轮胎). While Joe was  6 , the lady opened the window and began to
talk to him. She told him that she couldn't  7  him enough for helping her in such a situation. Soon Joe was
able to change the tire. She asked how much she owed (欠) him. Joe  8  thought about money. He told her
that if she really wanted to pay him back,the next time she saw someone who needed help, she could  9  that
person the help.
     A few miles down the road,the old lady saw a small restaurant. She decided to eat something and  10
 herself up before she finished her trip home. The waitress looked young and poor. After she finished her meal,
she handed a 100-dollar bill to her. When the waitress went to get her change, the lady left without being  11 .
The waitress then found some words on a piece of paper. "You don't owe me a thing. Someone once helped
me, the way I'm helping you. If you really want to pay me back, here's what you  12 . Don't let the chain (链)
of love end with you."
( )1. A. job     
( )2. A. although
( )3. A. put     
( )4. A. honest  
( )5. A. excited 
( )6. A. working 
( )7. A. pay     
( )8. A. once    
( )9. A. send    
( )10. A. warm   
( )11. A. watched
( )12. A. see    
B. place   
B. unless  
B. stopped 
B. safe    
B. surprised
B. thinking
B. love    
B. ever    
B. give    
B. put     
B. known   
B. want    
C. factory 
C. because 
C. set     
C. polite  
C. nervous 
C. looking 
C. thank   
C. seldom  
C. pass    
C. cheer   
C. noticed 
C. say     
D. house  
D. until  
D. parked 
D. nice   
D. shy    
D. talking           
D. praise 
D. never  
D. bring  
D. pick   
D. heard                        
D. do     
单项选择题