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问题 问答题 简答题

简述水产动物育种的优势？

答案

参考答案：1、育种潜力大；
2、遗传变异量大；
3、选择强度大，优秀性状易推广；
4、雌雄同体及性转促进了完全近交系的产生；
5、体外受精、体外发育；
6、种间杂交后代往往有生活力或可育。

选择题

清华大学的虞昊教授致力于第三代照明技术—LED灯的普及工作。LED灯的能耗小，造价低廉，使用寿命长。虞昊自制的LED台灯，用电压为6伏的电源供电，正常工作电流为300毫安。那么，此LED台灯正常工作时的功率为：   

A．1800瓦

B．180瓦

C．18 瓦

D．1.8瓦
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句型转换

句型转换。

1. The twin brother does well in math. (写出同义句)

   The twin brother _________ __________ at math.

2. She wants to see him as soon as possible. (写出同义句)

   She __________ ___________ to see him at once.

3. Sue is 15 years old. Lucy is 15 years old, too. (合并成一句)

    Sue and Lucy are _________ __________ age.

4. I always get up before six o'clock in my school days. (写出同义句)

    I __________ get up _________ six o'clock in my school days.

5. People are stressed out and angry. They might have too much yang in their lives. (用定语从句合并成一句)

    People ________ are stressed out and angry ________ have too much yang in their lives.

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