问题 单项选择题

选择差除以该性状的标准差称为()。

A、留种率

B、选择反应

C、世代间隔

D、选择强度

答案

参考答案:D

多项选择题
阅读理解

     One night last February, a seventeen-year-old Duffy drove home along a winding road, he saw a

strange light thrown against the tree. "I knew it wasn't the moon", he said. "I drive this road all the time

and I notice little things out of place."

     Duffy stopped his car and got out to examine. Below him far down in the deep valley lay a broken

car with its headlights on. Thirty minutes earlier, a man had driven off the edge of the road, which has no

guardrail. His car fell and rolled end over end, landing on its top more than two hundred feet below.

     Duffy rushed to call for help, then returned and got down to reach the injured driver. Snow covered

the valley and the temperature was below freezing. After struggling back up the cliff, Duffy took off his

jacket and shirt and wrapped the injured man in time, along with the blankets from his car.

    Life-saving deeds are starting to become usual action for Duffy, the oldest of seven children. When

he was 12, he saved his ten-year-old brother from drowning. Two years ago, his three-year-old sister

ate rat poison, and Duffy cleaned out her mouth, make her drink milk to protect her stomach and called

doctors.

     "We have tried to teach the children good values, and it looks like we have got some reward for it."

His father says.

1. The strange light came from ________.

A. The bright moon.          

B. Duffy's car.

C. The broken car in the valley  

D. an unknown place

2. The phrase" landing on its top" means the car lay_________.

A. on the top of the cliff    

B. with its wheels upward  

C. with its head upward    

D. on the road as usual

3. From the above article, we can see Duffy has saved ________ at least.  

A. two    

B. three    

C. four      

D. five

4. "We have tried to teach the children good values" may probably mean Duffy's parents often tell their

children_________.

A. to help people in danger        

B. how to save people's lives

C. to remember the value of the car    

D. how to do business